“Twenty-four members of the United States Congress have called for a public inquiry into the murder of Pat Finucane.
The solicitor was 39 when he was shot dead by loyalist paramilitaries in his north Belfast home.
His family have campaigned ever since for a public inquiry to establish the full scale of security force collusion.
The 24 signed a letter to Prime Minister Boris Johnson calling for such an investigation to be confirmed.
On Thursday Taoiseach (Irish Prime Minister) Micheál Martin confirmed he had also contacted Mr Johnson about the issue.
Mr Finucane, was a high profile solicitor who represented both loyalists and republicans – including prominent members of the IRA.
He was shot dead by loyalist paramilitaries, the Ulster Defence Association (UDA), in front of his wife and their three children.
In 2012 a government-commissioned review found agents of the state were involved in the killing and it should have been prevented, but also said there had been “no overarching state conspiracy”.
Mr Finucane’s widow Geraldine has campaigned for a public inquiry for many years.
The letter from the 24 members of the House of Representatives states: “The British government has refused to live up to its responsibility”.
“Now, nearly 15 years later, and several years after former Prime Minister David Cameron acknowledged “shocking levels of collusion” – and issued an apology to the Finucane family – we remain astounded that the British government has refused to live up to its responsibility, and is violating its commitments to establish the inquiry.”
Assistant General Secretary Celtic League (29th November 2020)