Being considered difficult is, according to mezzo-soprano Bernadette Greevy, too often another way of saying someone wants to do something as well as possible. As was evident at the National Concert Hall last week when singing Wagner's Wesendonk Lieder, Greevy remains a singer of international class, possessed of a rich, dark tone. At present, however, she is far more interested in discussing the Anna Livia International Opera Festival of which she is founder and artistic director. "I've stepped out of my own performance life for two years and I want the festival to succeed." The Government has contributed £300,000 towards the staging of it. The remainder of the cost - reckoned to be around £1 million - will be met by the corporate sector, private funding and the box office.

For Greevy the new 10-day event, which includes alternating performances of Massenet's Herodiade and Puccini's La Rondine, both conducted by Franz-Paul Decker, is not intended as a challenge to the existing opera calendar. "It is to fill a gap which is there. Most European cities have a summer opera festival, and I thought it would be nice to show ourselves off at a time when there are many visitors, as well as giving Irish singers an opportunity to perform with their international peers while giving home audiences a chance to applaud our existing talent."

She cast the two operas in consultation with a panel and is a believer in the audition system, which she put herself through for her performance of the title role in the Massenet work. It is a role she has sung before, at the Wexford Festival and in a semi-staged version at New York's Carnegie Hall, but as she says, "auditions are important. It's no use trying to do something if you are wrong for the part." Of the role of Herodiade she says: "It's a great part and very demanding; her character is different from the others in the opera in the sense that she demands things at any price, there is no compromise, she wants the head of John the Baptist - and she gets it. Audiences like the drama." Well aware of the flamboyant appeal of Herod's scheming queen, she adds: "She's like the Wicked Witch of the West."

There is a number of recitals on offer throughout the festival such as the English soprano Lynne Dawson and the Irish mezzo Margaret Maguire, while one of the highlights of the programme will be John Dexter conducting the works of Tallis, including the extraordinary motet Spem in Alium, written for five eight-part choirs and possibly the greatest achievement of early English music, in St Patrick's Cathedral on June 19th.

Greevy is a practical character and despite, or possibly because of, the dramatic glamour of her appearance, she enjoys presenting herself as the poised if subversive Dubliner who was born and raised on the north side and has never left - aside from performing some of the world's finest music, under some of the greatest conductors in some of the most exciting venues. While many, possibly herself included, would admit she has not been as fully recognised as she would have been elsewhere, Greevy has a huge repertoire and has single-handedly presented Mahler to the Irish people.

She would have been happy with her lot, though, had her husband, Peter Tattan, not died suddenly of a heart attack at 46 in 1983 leaving her alone with their son Hugh, then 14. "My personal life was destroyed in 1983; Peter's death was so unfair. I still think it is. It's 17 years now." She often speaks about him. There are many photographs. Another loss was that of Paddy, the second of her three brothers, 11 years ago, soon after he was diagnosed as having an inoperable brain tumour.

Unlike many international performers, she tries to down-play the artistic agony. She admits to being a worrier but tends to keep this to herself, and throughout her career the image she has presented in interviews has been that of a busy wife and mother who enjoys her home, rather than an intellectual. She is disciplined and must be more driven than she seems. As an artist she is supremely confident but as an individual she can be anxious and is alert to nuance. She has her critics in Ireland and knows it. Attention to detail is central to her personality, which moves between personable, to those who know her, and aloof, to those who don't.

When asked about music, the level of technical exactness she brings to her replies contrast with her chatty observations about the garden, or her hopes to restore her late husband's once-trendy Ford Capri.

On stage she is intense, passionate; her singing voice has many mood shifts and her attention to phrasing ensures that a song lives as text as well as music. "Many of these songs are poems; you simply have to place importance on the meaning as well as the sound of the words, otherwise you can't communicate with your audience." In person, she certainly has presence, although she is far smaller, an observation which amuses her. "It was far worse when I was young. Here I was: this skinny little girl with this big voice."

And big it is. Regardless of the number of performances you may have heard on stage or recording, nothing quite prepares you for the astonishing depth of sound she can create at close quarters. Sitting in her small, informal living-room, albeit one with a boudoir-grand piano, Greevy is animated, if never fully relaxed. In the course of describing something, she casually sings a few phrases from Mahler. The effect is impressive, underlining the difference between thinking you sound pretty good in the bath and being presented with a magnificent instrument. Her voice builds and fills the room. It is as if it is surrounding us. In master-classes she has often told students not to aim their voices at the ceiling: "If you can create a mellifluous space around the sound it gives a liquid feeling to the note whereas if you approach it with a hard, pushing movement that note has no place to go and you can easily go out of tune."

Her voice has made her famous, and has brought her to concert platforms and opera houses around the world. Does she feel in thrall to it? "It is part of me. It is part of what I am. It's where I go when I need strength. It is my core being. And it has never let me down. "Singing was always something I was good at," she continues. She was also good at drawing, a gift her son, Hugh Tattan, an animator, has inherited. The small hall of her house is a gallery featuring his sketches, including a portrait of her by him.

`It's always interesting seeing how your children see you," she says. "When I was a child we did lots of things: concerts, drill displays, drawing, Irish dancing. We were busy. Children were more active than they seem to be now. I liked school, which has become an unfashionable thing to say, and we were very fortunate at the Holy Faith. And then there was the fact that in my family singing was the most natural thing in the world. Mammy and Daddy loved music, and my brothers and my sisters and myself all sang."

The Holy Faith Clontarf was a good place for an aspiring singer. "Music played a huge role in our education. We used to do huge religious choir exams and secular choir exams - I learnt to read music by reading plain chant. We were always standing up performing - it does give you confidence - and there was the Feis." Greevy is one of several Irish international artists to have emerged through the intensive atmosphere of Feis competition. Although at first she was not always interested.

"I remember one of my first competitions and coming on stage dressed in an elaborate costume to sing an action song. I just didn't want to be there. I didn't want to do it. I raced through the song and sang so fast I left the accompanist behind and ran off stage." One of the judges called her back and asked why the rush? It was also pointed out to her that although she had the best voice, she wasn't going to win. She didn't. Greevy learned to slow down and enjoy performing. "My sister went in the following year, wearing the same costume, and won."

While she stresses they were all singers, Greevy "the sixth of seven children" still stood out even in a family of singers. By the time she was 16, her elder sisters had decided to do something about this gift and brought her to a Dublin singing teacher, Jean Nolan. It was the beginning and when she says "I could never have done any of the things I've done without the support of my family", she means it. On leaving school at 17 the singing continued. She went to London and studied at the Guildhall School of Music. There she enjoyed her piano lessons more than the singing ones and, though she had an impressive run of competition successes, was not encouraged by the voice teacher. She returned to Dublin but Jean Nolan died suddenly. Greevy began to study privately in London under Helene Isepp. It seems bizarre now but in the early stages of her career, Greevy, who received no funding from the Arts Council or anyone else, had to support herself by working for a cosmetics firm. At that time, a young pianist or violinist of a similar quality to Greevy would have fared better. "One of the problems for musicians is that we are not treated as `creative'; we are only interpreters."

Greevy's London debut at the Wigmore Hall was more than just another successful recital: "It started me off, and I never looked back." As a singer who has performed in symphonic works, oratorio and opera, including Wagner's Das Rheingold and Verdi's Don Carlos, she remains committed to the recital and fears for its future. Classical singers have always been an exotic minority, and while the current trend for crossing into the popular repertoire when recording has widened the audience, it has affected the purity. Nowadays, sopranos have recorded selections ranging from arias to musicals. It is also true, of course, that sopranos and tenors have more commercial appeal than mezzo-sopranos and baritones, but then Greevy has never had to battle in the market place. Nor does she intend to.

As a young singer she impressed the great conductor, John Barbirolli. She sang in his production of Messiah and also performed in Verdi's Requiem and Elgar's The Dream of Gerontius. Before any of that, though, she had taken another vital step. She was asked if she would learn Mahler and was able to reply that she had just been given the score of the Wayfarer Song Cycles for her birthday.

It was to prove one of the most important collaborations not just of her career but of her life. "Mahler is so special; his music is about feeling and emotion. There is such depth." Next year she sings in Mahler's Symphony Number 8 in Barcelona. Her recording of his orchestral songs cycles, including the Kindertotenlieder, Lieder eines fahrenden Gesellen and Ruckert Lieder, is wonderful.

Brahms and Schubert are also important to her, while she says of her recording of Bach Arias, which includes Erbarme dich, mein Gott from St Matthew Passion: "I think I am most proud of that." On it she performs with the New Irish Chamber Orchestra, conducted by John Beckett, whom she praises. "He is wonderful. Ireland should never have let him leave."

As a child, Greevy had been very aware of the great British contralto Kathleen Ferrier, who died in 1953 at the age of 41. "One of my brothers was a great fan so I was used to hearing her." Another of her own favourites is the Swiss soprano Lisa della Casa, one of the loveliest voices of all time. Greevy says, "here's a treat now" and reaches for a CD. It is della Casa singing Richard Strauss's Vier Letzte Lieder (Four Last Songs). Greevy listens as the beautiful sound soars and says, "now that's great singing". She also admires Victoria de los Angeles. As a young singer, Greevy appeared in performance with the British mezzo Dame Janet Baker - "a great voice" says Greevy. Baker, however, retired at 49. Greevy shows no signs of needing to.

Respected as a professional, she has also been criticised for being a perfectionist. Her performance as Carmen in a concert performance production at the National Concert Hall in 1996 divided opinion. Greevy could certainly sing the part but could she act it? "I enjoyed it. I think Carmen the character fascinates everyone. She is dangerous and fickle. We all know characters like that; when they walk into a room, everyone stops. They can be any age. I wish I'd done it a long time ago."

French is difficult, she says. "The accent is very hard, harder than German, which I think sounds more beautiful when sung than spoken. But I love the French repertoire." In 1989 she recorded Berlioz's Les Nuits d'Ete Op 7, as well as a number of songs by Henri Duparc (1848-1933) with the Ulster Orchestra under Yan Pascal Tortelier. There is a lightness and melancholy about the pieces, and she is delighted to have introduced many to Duparc. "Italian is the most beautiful because it flows with the voice, as does Latin which I love to sing . . . I do think English is difficult because we speak it in a colloquial way, so it is not clear when we sing it."

Is she a diva? "Well a diva can mean a million things. Some friends call me Diva; it is a term of endearment. But it is also a way of saying someone is difficult for no other reason than being difficult. Then again, if it's used in the proper way, it's like an honorary title you get after you've earned it. But like everything, it can be used in many ways."

Artists should work together, she says. "A singer and an actor should be able to say to a ballet dancer, `let's do something'. I think if we in the arts worked together we would be a formidable force. It always has been difficult for artists." Ever the practical realist, she looks out over her neat back garden and points to the villa-style wall which she had built with the fee from a performance. "I'll always be able to sing, but there will come a time when I won't want to go through the rigours of a public performance and the responsibility all that brings."

Nothing is easy, she says with a smile and then recalls a recent radio interview when she announced she wanted the closing moments from IT]Gotterdammerung played at her funeral. "I think the interviewer thought it was too much," she says, reaching for the CD and playing the piece. "It's a great leave-taking isn't it?" Having created an opera festival, what does she want to do next? "Stage a Wagner opera in Dublin. It can be done. We should."

The Anna Livia International Opera Festival at the Gaiety Theatre, Dublin runs from June 16th to June 25th. Phone: 01-6771717