Relatives of Omagh bomb victims met Minister for Justice Alan Shatter to demand a cross-border inquiry into the 1998 atrocity.
They handed over an independent report of a specially commissioned review of all the investigations and court cases held since the Real IRA bombing in Omagh.
29 people, including a woman pregnant with twins, died in the blast.
The British government received a copy of the report a month ago.
The families are also seeking a joint meeting with Northern Ireland Justice Minister David Ford and PSNI Chief Constable Matt Baggott.
One of the report's authors, Martin Bridger, a former head of investigations at the Northern Ireland Police Ombudsman's Office, will be accompanying the delegation.
Michael Gallagher, whose son Aidan was killed in the bombing, led the delegation.
He said Mr Shatter told them he "would personally consider and reflect on the report.
"He acknowledged there are likely to be some very unpalatable issues that have arisen and he will need to share it with the Garda Commissioner," Mr Gallagher added.
