Intelligence gathered by MI5 ahead of the Omagh bombing was passed to police only this year, the chief constable has confirmed to victims' families.
Sir Hugh Orde met the Omagh bomb victims' families
Michael Gallagher was part of a delegation of relatives who met Sir Hugh Orde and his senior officers.
He said it might have made a difference if the information was passed on before the attack, which killed 29 people.
Mr Gallagher said the two-hour discussions were "very long, at times difficult and sometimes very frank".
"We talked about the way things had been handled, the intelligence, particularly MI5," he said.
"He confirmed that it was only earlier this year that the PSNI was aware of that intelligence for the first time. It was important for us to hear it from the chief constable.
"That was something outside his control, but nevertheless we believe it could have made a difference and the police in Omagh had a right to know that intelligence so that they could at least have had a chance."
Mr Gallagher added: "It may or may not have had a bearing on the Omagh bomb but at least it would have raised the state of awareness that there was a bomb attack on its way."
Mr Gallagher's son Aiden was one of 29 killed in the Real IRA attack in August 1998.