The victims of one of the worst days of atrocities in the Troubles should be told the truth, a campaigner has said.

A wreath-laying ceremony took place at a Dublin memorial to 33 killed by loyalist bombers and their families want the British government to release classified security files relating to deaths in which state collusion is suspected.

It marked the 44th anniversary of the blasts when paramilitaries detonated four no-warning bombs in Dublin and Monaghan on 17 May 1974.

The Justice for the Forgotten lobby group has fought a long-running campaign for an open inquiry into allegations that British security agents colluded with the terrorists to plot the co-ordinated and sophisticated attacks.

Spokeswoman Margaret Urwin said: "When people talk about justice they are often meaning prosecutions and so on.

"We have been campaigning now for 25 years, since 1993 basically.

"What the families have always asked for, demanded, is for the truth rather than prosecutions.

"I don't think they ever expect justice in that sense but what they really want to get is as much of the truth as possible."

The British Government has begun consulting on measures to address legacy issues, including mechanisms to reinvestigate past wrongdoing and many unresolved killings.

They were originally agreed in 2014 as part of the Stormont House Agreement involving political parties in Belfast and the British and Irish governments.

Political paralysis at Stormont delayed full implementation of the deal.

Ms Urwin added: "We hope that the mechanisms of the Stormont House Agreement will soon be established. That may also help in freeing them up a bit more to release these documents."

Minister for Justice and Equality Charles Flanagan, Lord Mayor of Dublin Micheal MacDonncha and Chairman of Monaghan County Council Cathy Bennett took part in today’s ceremony on Talbot Street.