A referendum to change the Constitution to allow for marriage or adoptions by gay couples would not be passed by voters, the Taoiseach said yesterday.
However, Mr Ahern said he was prepared to change legislation to ensure that gay couples could inherit property and pension rights from each other and qualify for tax entitlements currently enjoyed by people who were married.
The Taoiseach, who is leading a trade mission to India this week, was speaking after the publication of details of a report from the Oireachtas All-Party Committee on the Constitution.
The Oireachtas committee is due next week to advise the Government not to change the definition of the family currently enshrined in the Constitution because of fears that such a move could spark a divisive referendum centred on gay marriage. Instead, it will recommend legal changes to create civil partnerships for cohabiting and same-sex couples, which would offer them "marriage-like" privileges.
Details of the report's recommendations prompted criticism yesterday from groups such as the Gay and Lesbian Equality Network (Glen), which said that it discriminated against same-sex couples. However, the group's spokesman, Kieran Rose, welcomed the recommendations relating to civil partnerships.
The One Person Exchange Network (Open), which represents 80 lone parent groups , said that it was "very disappointed" with the recommendation. "Anything that would maintain the tiered family system we have at the moment would be heart-breaking. It makes you wonder how they could come to this conclusion given the growing diversity of parents and families," said the director of Open, Frances Byrne.
Two members of the 14-person Oireachtas committee, the Green Party's Ciarán Cuffe and Labour's Jan O'Sullivan, said that they wanted recommendations which would better reflect the changing nature of the Irish family. Mr Cuffe said: "Several of us on the committee felt that all persons, irrespective of their marital status, should have a right to family life."
Separately, the Children's Rights Alliance, a block of 80 groups across the childcare area, called for a referendum to articulate children's rights in the Constitution. This is one of the Oireachtas committee's recommendations.
The group's chief executive, Jillian van Turnhout, said: "The implications of not articulating children's rights are real: for example, children will remain in abusive situations, children will not see both of their parents regularly, children will remain in foster care for years with no hope of being adopted into their new families."
Speaking in New Delhi, Mr Ahern said that he had met a number of groups representing gays and lesbians in recent years. However, he had not been asked by any of them to allow same-sex marriages.
"They have continually stated to me that the kind of issues they want addressed are primarily ones to do with inheritance, ones to do with insurance rights," he told The Irish Times.
Asked if he believed that a constitutional referendum which would allow for gay marriages would be passed, the Taoiseach said: "I don't, though there have been no opinion polls on it.
"At this stage, that could be a divisive issue, particularly when the proponents who are coming to me have not asked for that. What I would rather do is deal with the issues that they have asked for."
Mr Ahern, who emphasised that he had not seen the final report from the all-party committee, added: "I can never be sure what would happen in a referendum. I have gone in to win referendums and lost them on two occasions. I went in on six occasions and won them.
"So I would rather do the things that I think I can usefully do. Perhaps on other days people can do other things."
He said he had indicated last year that the Government should make "legal changes" to give better protection to gay and cohabiting couples.
"I think at the moment there are issues of inheritance, of tax, of transferability of properties that we can usefully look at. Most of those issues are in the area of finance."