A US group of Irish American political leaders and diplomats has criticised the UK government's proposed amnesty to address the legacy issues of the Troubles, describing it as alarming to human rights experts.

Under the proposals, the British government would create a proposed statute of limitations which would end all prosecutions for incidents up to April 1998 and would apply to military veterans as well as ex-paramilitaries.

The proposals, which British Prime Minister Boris Johnson said would allow Northern Ireland to "draw a line under the Troubles", would also end all legacy inquests and civil actions related to the conflict.

The Ad Hoc Committee to Protect the Good Friday Agreement has written to Mr Johnson to express what it described as its dismay over the plan.

"We find this proposal to be at odds with both the spirit and architecture of the Good Friday Agreement," the letter states.

"We have strong reason to believe that this proposal will not be met with approval in Washington by either Congress or the Biden Administration. It will be a further source of disagreement with US political leaders who have already raised serious concerns about your government's recent approach to implementation of the Northern Ireland Protocol," according to the letter.

The co-chair of the Ad Hoc Committee, James Walsh said they intend to raise their concerns with senior US administration leaders at both the State Department and the White House National Security Council.

"This December, President Biden will convene his Summit on Democracies. I have to believe that this proposal will become an issue of contention at that Summit unless the Prime Minister pulls it back," Mr Walsh said.

The Ad Hoc Committee was formed over two years ago by leading political leaders and diplomats who have a history of supporting the peace process in Northern Ireland.

The group includes five former US Ambassadors, several former US Special Envoys to Northern Ireland as well as leaders of Irish American organisations.