Relatives of victims of the 1998 Omagh bomb will commemorate the fifth anniversary of the atrocity today.
The 500 lb car bomb, planted by the "Real IRA", killed 29 people, including a woman who was pregnant with twins, and injured more than 200 others
After a service in the town today, the British Prime Minister, Mr Tony Blair, will face new demands for a public inquiry into the atrocity.
Even though his government has pledged £800,000 to help pay the costs for an unprecedented civil action against five men blamed for the attack, it is understood relatives will heighten pressure for a full judicial investigation.
Despite massive police investigations on both sides of the Border, nobody has been charged with any of the murders.
Detectives insist they can still catch the men who planned and carried out the bombing, but relatives remain frustrated and angry that five years on no one has been caught.
Colm Murphy (50), a publican and builder, is serving a 14- year prison sentence for conspiring to cause an explosion, but the role he played in the bombing, as outlined at his trial, was a minor one. He has since appealed his conviction.
"I would certainly, as far as seeking justice is concerned, like to see someone specifically charged with the events of August 15th, 1998," Mr Victor Barker said yesterday. Mr Barker's 12-year-old son James was among the dead.
The relatives' call for a public inquiry is set to be reiterated following a brief service today and a minute's silence at the memorial garden built close to where the bomb devastated the town.
A list of reasons will be given why a hearing similar to Lord Saville's tribunal into Bloody Sunday is needed.
Mr Michael Gallagher, chairman of the Omagh Victims Group, said yesterday: "We don't want to become martyrs of justice here, we want justice, and there is a resolve within the families here to continue to press for that."
Mr Gallagher's 21-year-old son Aiden was among those killed.
The families are also due to thank the emergency services publicly for their work in helping hundreds who were injured in the carnage.
However one Omagh man bereaved in the explosion will not be at the service.
Instead, Mr Laurence Rush, whose wife, Elizabeth, was among the dead, plans to get through the painful day in quiet reflection.
He said: "I will take some flowers from the garden and go to the grave. My wife won't be there, but it's nice anyway. You just do what has to be done. This is a long sentence." - (PA, Reuters)