Nationalist politicians have backed 3,500 relatives of people killed during the Troubles in their call for the British and Irish governments to implement the legacy elements of the Stormont House agreement.
The call came in an open latter to British prime minister Boris Johnson and Taoiseach Micheál Martin, which was printed in newspapers in Ireland and America yesterday.
The letter has been signed by relatives of people killed by loyalist, republican and state players during the Troubles.
Struck in 2014, the Stormont House Agreement included mechanisms for how to deal with the past.
The deal included provision for setting up a Historical Inquiries Unit, an Independent Commission on Information Retrieval, an Oral History Archive and the creation of an Implementation and Reconciliation Group.
The British government has failed to implement the terms of the agreement and has suggested proposals to limit historical investigations.
Concerns have also been raised that the London government is considering an amnesty for British soldiers.
In the letter relatives urged both governments to fulfil the commitments made in the agreement.
"We the below signed wish to state that the Stormont House Agreement was a compromise, however it offered a human rights pathway to addressing our rights as citizens and as bereaved relatives," they wrote.
"This would address the legacy of state impunity and independently investigate all actors equally."
Sinn Féin assembly member Linda Dillon has backed the call for full implementation of legacy mechanisms.
"It is unacceptable that the families have had to take this step," she said.
“I commend their dignity and determination and offer them our ongoing support.
"Without addressing the legacy of the past the task of reconciliation is made so much harder."
SDLP leader Colum Eastwood called on secretary of state Brandon Lewis to honour agreements reached on dealing with the past.
“The British Government’s attitude to legacy is tone deaf," he said.
"In spite of agreed structures, institutions and processes for dealing with the legacy of conflict in the north, which represent a substantial compromise by all parties, Brandon Lewis has made statements which amount to a unilateral withdrawal from those commitments," he said.
“The way victims have been treated over the course of the last year is a disgrace and the Secretary of State should be ashamed.
"The failure to engage with them and with their representatives is an appalling dereliction of responsibility."
The Northern Ireland Office said: "The UK Government remains committed to finding a way forward on legacy issues, which have remained unresolved for far too long.
"The government recognises that there are many different views on how best to move forward, which is why the Secretary of State for Northern Ireland will continue to engage with all communities across Northern Ireland and beyond to find a way forward that puts information recovery and reconciliation at its heart. We welcome the contribution of the relatives of Troubles victims to this process."
Mark Thompson, chief executive Relatives for Justice, which organised the letter, previously said about half of those who signed are 35 years and under.
"This represents the current and future generations and underlines the ongoing trauma and intergenerational impact that the killing of a relative has also had on surviving families," he said.
Senior American AOH member Martin Galvin said that it and other Irish American organisations are holding a webinar involving relatives in a bid to mobilise support in the US this weekend.