Irish reactionPresident Mary McAleese joined a steady flow of political and religious leaders, foreign ambassadors and members of the public in calling into the British embassy in Dublin yesterday to sign a book of condolences.
British ambassador Stewart Eldon said: "We have been overwhelmed by the volume of calls and messages from people in Ireland expressing their sympathy and shock."
The book of condolences will remain open at the embassy between 10.30am and 4pm on Monday and Tuesday.
Dublin City Council is opening a separate book of condolences at the Mansion House next week. It can be signed between 11am and 4pm on Monday, and between 10am and 4pm for the rest of the week.
Another book of condolences has been opened at Derry's Guildhall by the city's mayor.
Taoiseach Bertie Ahern ordered flags on State buildings to fly at half-mast yesterday.
Prayers will be said for the victims of the blasts at religious ceremonies over the weekend, while a minute's silence will be observed at various sporting fixtures.
People concerned about missing Irish citizens can contact the Department of Foreign Affairs emergency phone number at 1800 242548.
Irish citizens living in the UK can contact the Irish Embassy in London at 0207 2012508 or 0207 2012501.
People concerned about British citizens can call the British embassy in Dublin at (01) 2053700.