Some of the relatives of the victims of the Omagh bombing have again called for a full cross border public inquiry into the Real IRA attack.
Twenty-nine people died in Omagh bombing in August 1998
Twenty-nine people, including two unborn children, died in the 1998 bombing of the County Tyrone town.
More than 300 people were injured in the blast on 15 August after a car bomb exploded during a busy Saturday afternoon when the town was packed with shoppers.
It was the worst single atrocity in 30 years of violence in Northern Ireland.
The call came after a service marking the fifth anniversary of the blast.
The memorial garden, just a few hundred yards from the site of the explosion, was the venue for Friday's commemoration.
The service was attended by relatives of those who died from Omagh and Buncrana in the Republic of Ireland, as well as representatives of the two Spanish victims.
Also present were Security Minister Jane Kennedy and Assistant Chief Constable of the PSNI Sam Kincaid.
However, Ms Kennedy said she did not see the need for an inquiry and said the focus should remain on the criminal investigation.
"Obviously, we will want to listen to what the families are saying but my own instinct at this moment is that the focus is upon the criminal investigation," she said.
Irish junior minister Noel Ahern said his government was also committed to bringing those responsible for the 1998 bomb attack to justice.
"Both governments have brought in legislation which has helped but obviously, there are people out there with information," he said.
"It is a matter of deep regret that those people have not come forward with the information which would allow the authorities on both sides of the border to put the perpetrators behind bars."
Friday's service was the last time the anniversary will be officially marked.
Next year, some of the families of those who died will hold their own event.
Kevin Skelton, who lost his wife Philomena in the atrocity, said he was glad it was the final official commemoration, and said the attack "seemed like yesterday".
He added: "The years seem to roll by but it just seems like days rather than years. It gets no easier."
Ms Kennedy said the focus remained on the criminal investigation
Only one man has been convicted in connection with the bombing.
Colm Murphy was sentenced to 14 years in prison in January 2002 for plotting the bombing.
Meanwhile, the deputy chairman of the Policing Board, Denis Bradley, has appealed to dissident republicans to declare a ceasefire.
Earlier this week, live bullets were sent to Mr Bradley's home and last month a hoax bomb was left near the premises. Police said dissidents were behind both incidents.
Last week, the man said to be the leader of the Real IRA, Michael McKevitt, was sentenced to 20 years in prison for directing terrorism and being a member of an illegal organisation.
However, his conviction did not include Omagh as the legislation under which he was tried was only introduced after the atrocity.
A group of relatives is currently pursuing a civil action against five men they blame for the attack.
Last week, the government announced it was to give £800,000 to help toward the cost of bringing the £1.5m case to court.
It is understood to be the first time the government has helped to fund a civil prosecution and a government spokesman said it was because the situation was "totally exceptional".