Families of the Omagh bomb victims are to meet the Taoiseach in Dublin for the first time on Tuesday.
They are expected to quiz Enda Kenny on actions arising from a confidential report which they handed to the British and Irish governments more than three years ago.
Michael Gallagher, who lost his son Aiden in the 1998 bomb attack, has previously criticised Mr Kenny’s failure to meet with Omagh victims since taking office in 2011, but described Tuesday evening’s meeting as “significant”.
He said: “Mr Kenny met us before when he was in the opposition but his priorities seemed to change when he became Taoiseach.
“He has met many other victims and individuals but he has always seemed to avoid us.
“It will be a significant meeting but, let’s see what comes out of it.”
Twenty-nine people, including a woman pregnant with twins, were killed and more than 200 were injured when a 500lb car bomb, planted by the Real IRA, ripped through the Co Tyrone market town in August 1998.
It was the single worst atrocity of the Troubles.
Members of the Omagh Support and Self Help Group, which represents some relatives, have been calling for a full public inquiry for 14 years. They have been backed by Amnesty International.
The families believe there was a failure to share intelligence which could have prevented the dissident republican bombing and their wide-ranging report has raised questions about police investigations on both sides of the Irish border.
Mr Gallagher said they would be demanding answers.
“We delivered a confidential report to the Irish government on July 19, 2012. We have not really had any response to that,” he added.
“We will be wanting to know what the Irish government has done with the document; what actions they have taken and how do they propose to address the issues raised.”