The Taoiseach, Mr Ahern, has been criticised for failing to attend the fifth anniversary of the Omagh bombing.
The Government said it is committed to convicting those responsible for the "Real IRA" bomb which killed 29.
Mr Michael Gallagher, of the Omagh victims' group, said he was "disappointed" that Mr Ahern did not travel to Omagh for yesterday's special commemoration ceremony, particularly as he was holidaying in Co Donegal.
He also believed the British Prime Minister, Mr Tony Blair, should have been in Omagh yesterday. "Yes, we are disappointed, but we are grateful for the people who did come," he said outside the memorial garden in Omagh where about 400 people gathered for the ceremony.
Survivors, as well as relatives and friends of the victims, attended the ceremony in remembrance of the 29 people and twin unborn girls who died in the "Real IRA" car bomb attack on August 15th, 1998.
The moving ceremony of prayers, scriptural readings and music reflected the grief of the injured and bereaved and the continuing search for the truth behind who was responsible for the attack and how they carried it out.
There will now be no more civic or public commemorations until the tenth anniversary of the bombing which, according to some of the families, will allow them time and space to deal more privately with their grief.
The families, however, are still adamant that those responsible for the attack must be apprehended and prosecuted. They called for an independent inquiry into the bombing.
"After five years of criminal investigations, we are now calling on the Dublin and London governments to give us a full cross-Border public inquiry," said Ms Caroline Gibson, whose sister Esther was killed in the attack.
"To date, we have had six investigations into Omagh without convictions and we now want the truth about what happened on that fateful day," she said in a statement read after the ceremony.