There was a “manifest failure” of the UK and Irish governments to adequately respond to the Dublin and Monaghan bombings, Ireland’s president has said.

A wreath-laying ceremony was held in Dublin to mark the 50th anniversary of the deadly attacks on May 17 1974 when three no-warning bombs went off across Dublin city centre and one in Monaghan town.

No-one has ever been convicted over the bombings but the loyalist Ulster Volunteer Force (UVF) admitted responsibility in 1993.

Justice demands that they deserve the truth - no more, no less

It remains the biggest loss of life on any single day of the Troubles.

The ceremony took place in Talbot Street, Dublin, where an official memorial honours the 35 people killed in the bombings, including two unborn babies.

Another 300 people are estimated to have been injured in the blasts.

President Michael D Higgins said: “Even in the context of the many atrocities committed at that time, the Dublin and Monaghan car bombings of 1974 were crimes of a particular level of savagery, executed consciously upon workers and civilians with total disregard for human life and suffering.

“Like the families of so many other victims and survivors of the Northern Ireland conflict, so many of you here today have been trying to find answers about what happened.”

Mr Higgins said it is a “matter of profound regret” and “unacceptable” that no one had been held accountable for the atrocities.

The president said systemic failures at state level include possible collusion between security forces and loyalist paramilitaries, the disappearance of important forensic evidence and a refusal to supply information.

He said: “The manifest failure of both the British and Irish governments to initiate suitable responses in the aftermath of the attacks has left a legacy that cannot be left unaddressed.

“I share with the relatives gathered or represented here their feeling of being abandoned and failed by the system, of their being denied justice for the loss of loved ones.”

Mr Higgins said the relatives need more than an empathetic ear, adding: “Justice demands that they deserve the truth – no more, no less.”

The president also criticised the current British Government’s Legacy Act, saying: “The enactment of that unilaterally sourced legislation has resulted in families who have spent decades fighting for an effective investigation into their cases of not only facing further uncertainty and delays but of the deprivation of legal rights.”

Mr Higgins said there was a collective responsibility to deal with legacy issues in an ethical manner, adding: “A strategy of feigned amnesia, or hoping time will deliver one, is simply not an option, nor is any strategy of continuing the protection of previous evasions or failures to act.

“It is not morally acceptable, nor is it politically feasible, to request that those affected by such tragedy should forget about the past, draw a line or move on in the name of any naive desire for a supposed closure that may never be attainable.”

He said the families’ call for the full truth to emerge should be supported, “however embarrassing or painful it may be”.

Ireland’s premier Simon Harris and deputy premier Micheal Martin also attended the event organised by the Justice for the Forgotten group which represents bereaved families and survivors.

PSNI Chief Constable Jon Boutcher and Sir Iain Livingstone, who leads the Operation Denton operation, were among other attendees.

Former Irish premiers Leo Varadkar and Bertie Ahern were also present.

Mr Harris said: “Today, 50 years on from that dark day, I remember all those who lost their lives and were injured, and think of their families.

“I know their hurt has been compounded by a lack of truth and of justice for the victims since, and of immediate support for the families in the difficult years that followed.

“Today, we honour the memories of those who died, the more than 300 people injured, and the bereaved, both those living and those who have died in the years since.

“Today, Dublin and Monaghan remember.”

Mr Higgins will lay another wreath in Monaghan on Friday evening, where local minister Heather Humphreys will represent the Government.

Before the Dublin ceremony, Mr Martin and Mr Boutcher attended a memorial Mass at nearby St Mary’s Pro-Cathedral.

Leading the service, Archbishop Dermot Farrell read out the names of those killed in the bombings.

Calling for reconciliation, he added: “Pray that those with the power to be able to deliver that justice, which will ultimately bring peace, will come quickly so that all may be fully healed of that awful atrocity and tragedy.”

Earlier, Mr Martin pledged that all Government-held files in connection with the bombings should be released to inquiries.

He said: “I’ve a general view that any files we have in Dublin, or within the Department of Justice or in An Garda Siochana, should be released to all inquiries in respect of atrocities in Northern Ireland.

“Today is a very poignant day and the Justice for the Forgotten group has been extraordinary in their efforts they have made to focus attention many decades on, on what was the worst atrocity, in what was a terrible time in Ireland when there was murder and mayhem across the land.

“Earlier governments from the 1990s on, we had two inquiries and both those inquires made it very clear that they didn’t get full co-operation, particularly from the British state.”

Mr Martin told RTE’s Morning Ireland radio programme that the Legacy Act had created a “huge challenge”.