Six members of the US Congress have written to the British Embassy in Washington expressing concern about a Troubles amnesty and the Government's failure to implement legacy mechanisms in Northern Ireland.

In a bi-partisan initiative, the letter was signed by Peter King, Eliot Engel, Chris Smith, Brian Fitzpatrick, Nita Lowey and Brendan Boyle.

The Congress members cited their fears about a proposed statute of limitations for security force members as well as the delay in establishing legacy mechanisms agreed as part of the 2014 Stormont House Agreement. These include a Historical Investigations Unit.

In their letter to the deputy British ambassador Michael Tatum, the Congress members said some of their constituents were deeply concerned about recent developments.

"Examination of legacy killings in Tyrone and South Derry, British military studies, the de Silva report, Stevens Inquiry, Ombudsman investigations, and court transcripts, have raised many questions from the relatives of those who were killed.

"These relatives have expressed concern about Government collusion in these killings and fear that they will not know the truth behind what happened to their family members.

"This anxiety has been magnified by the potential consideration of a new statute of limitations for British military and constabulary. As members who have a continuing interest in Northern Ireland, we wish to convey these concerns about this important issue to you, and our desire that legacy issues be resolved to heal the wounds of the past."

The letter was welcomed by Ancient Order Of Hibernians (AOH) Freedom-for-all-Ireland chair, Martin Galvin.

"The AOH continually hears from victims' relatives, who tell us that American pressure, particularly from members of Congress, is vital to their fight for truth," he said.

"These families are now concerned that the incoming British regime, headed by Boris Johnson, would not hesitate to sacrifice Irish legacy justice for Westminster political gains."

Belfast Telegraph