There will be no public inquiry into the Omagh bombing Secretary of State Theresa Villiers has said.
Ms Villiers said there were not "sufficient grounds to justify a further review or inquiry".
Twenty-nine people were killed in the Real IRA attack after a massive car bomb exploded in the Co Tyrone town.
On Thursday morning it was announced that she has decided not to instigate a public inquiry into the circumstances over the Real IRA bombing in Omagh on August 15, 1998.
"I do not believe that there are sufficient grounds to justify a further review or inquiry above and beyond those that have already taken place or are ongoing," she said.
The Secretary of State for Northern Ireland said it had not been "an easy decision" and that "all views were carefully considered".
Families of those killed in the attack last month called for a full public inquiry into the atrocity.
"I believe that the ongoing investigation by the Office of the Police Ombudsman for Northern Ireland is the best way to address any outstanding issues relating to the police investigation into the Omagh attack," she added.
"The fact remains that the Real IRA carried out the bombing in Omagh on August 15, 1998, murdering 29 people and injuring many more.
"Responsibility is theirs alone. I sincerely hope that the ongoing police investigation will bring to justice those responsible for this brutal crime."
"I have met representatives of the Omagh Support and Self Help Group, as have a number of my predecessors as Secretary of State. I have offered to meet them again to explain my decision further if they wish."
All these views were weighed against other factors, including the series of previous inquiries into the Omagh bomb and the current investigation by the Office of the Police Ombudsman for Northern Ireland, the NIO said.
The Co Tyrone blast was one of the worst atrocities in the Northern Ireland conflict and relatives have called for an all-Ireland probe into whether the authorities could have done more to prevent it.
Speaking to Sky News, Michael Gallagher, whose son Aidan was killed in the bomb attack said he was "absolutely disappointed but not surprised".
He described the reasons given by Ms Villiers for ruling out a public inquiry as "trivial".
"Those people didn't need to die and yet here we have the Secretary of State saying we cannot have a public inquiry."
"We gave both governments a document over a year ago that shows that both the British and Irish government could have done something to prevent the Omagh bomb," he said.
"We have the result now - it's not the result we wanted but at least we can move forward. We can go to the courts and that's exactly what we will do."
The 1998 bomb attack killed 29 men, women and children, as well as unborn twins, in what was the most devastating act of terrorism of the Troubles.
Nobody has been convicted for the attack.
But a civil action in 2009 resulted in four men being found liable for the atrocity.
They were found liable for the bombing in a landmark civil case taken by some of the bereaved relatives and ordered to pay £1.6 million compensation.
Families of Omagh bomb victims have vowed to take the British government to court after branding its decision to rule out a public inquiry into the attack as a feeble bid to hide from the truth.