There is more information available from British authorities on the Dublin and Monaghan bombings, the Taoiseach, Mr Ahern, said today.
Speaking at a 30th anniversary ceremony of the bombings, which killed 34 people, the Taoiseach said that British Prime Minister Tony Blair is unable find additional evidence that would aid a public inquiry, but that does not mean it does not exist.
The loyalist Ulster Volunteer Force has admitted carrying out the bombings but no-one has ever been brought to account for the devastating explosions.
Justice Henry Barron's 300-page report, published in December, was critical of the Government at the time of the bombings and of the original Garda investigation, but found no evidence of British security force collusion.
The ceremony on Talbot Street, Dublin today. Photo: Carl O'Malley
"I find it hard to believe that there is no information," said the Taoiseach today. "I believe Tony Blair when he says that they can't find it but whether that information is in British security systems or wherever, this is the dilemma that we have had for the last four to five years."
The Taoiseach was responding to calls, from the Justice for the Forgotten group, for more pressure to be put on the British government to co-operate with a public inquiry into the 1974 bombings.
Speaking to ireland.comat a memorial service on Dublin's Talbot Street, chairwoman for the campaign Ms Bernie McNally said that the inquiry has been "sidelined" for too long.
"The Irish Government have got to carry out their duty in a responsible way and pressurise Tony Blair to conform," said Ms McNally, a survivor of the bombings which killed 34 people on Talbot Street, Parnell Street, and Nassau Street in Dublin, and in Monaghan town.
In her address to the assembled crowd - comprising survivors, family members of the deceased, trade unionists and the Taoiseach - Ms McNally labelled Mr Blair a "hypocrite" as he claims to be wiping out terrorism, while he ignores the plight of those affected by the bombings.
The Taoieach, Mr Ahern
The Taoiseach looked on as wreaths were laid at the memorial statue, to the music of a lone piper, and later fielded questions from the press and members of the campaign.
"We have done substantial work over the last five years and we have to keep at it," Mr Ahern added, before defending the recommendation of the Barron report that any inquiry should be held in Northern Ireland.
"We could be here having an inquiry but 49 of the top 50 people we want couldn't come, so we wouldn't actually achieve anything," Mr Ahern said.
"The bombings left a legacy of pain and sorrow.
"The testimony of the people who told their stories with such dignity and eloquence before the Joint Oireachtas Committee on Justice, Equality, Defence and Women's Rights was deeply moving."