DUP Leader Sir Jeffrey Donaldson has written to the Prime Minister urging him to scrap controversial legislation to address the legacy of Northern Ireland's Troubles.
Sir Jeffrey said that an "amnesty for terrorists is not only an affront to justice but a gateway to further attempts to rewrite and airbrush the past".
Speaking in the Commons on Wednesday, Northern Ireland Secretary Chris Heaton-Harris said he did not think he would ever be able to persuade the DUP to support the Bill.
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The Northern Ireland Troubles (Legacy and Reconciliation) Bill proposes an effective offer of immunity from prosecution for perpetrators of crimes during the Troubles who co-operate with a truth-recovery body.
It would also halt future civil cases and inquests linked to killings during the conflict.
While the Government introduced a number of amendments to the Bill earlier this month, the Stormont parties, Irish government and victims' groups remain opposed to it.
The legislation is set to return to the House of Lords on Wednesday.
The DUP leader said: "The Government's legacy proposals have been rejected by the vast majority of victims and survivors, who suffered the most during the Troubles and who still live with the terrible legacy of pain, trauma and loss.
"An amnesty for terrorists is not only an affront to justice but a gateway to further attempts to rewrite and airbrush the past.
"As things stand, the only condition placed on a terrorist seeking immunity is that they give their account of the acts of terrorism they were involved in.
"There is absolutely nothing in the way of protection for those families who they terrorised and left without fathers, mothers, brothers and sisters. Indeed those who fled criminal proceedings in Northern Ireland could return to avail of the scheme without any repercussions.
"This is wrong. It is not too late for the Prime Minister to do the right thing and choose the side of justice and innocent victims."
Sir Jeffrey said it was not too late for the Prime Minister to halt the Bill.
He added: "I have urged Rishi Sunak to recognise that imposing this Bill against the express wishes of communities and political parties in Northern Ireland would be a retrograde step.
"Reconciliation will not be achieved by sacrificing justice. Access to justice must be preserved and the principle of everyone be equal under the law should be protected.
Speaking in the Commons, shadow Northern Ireland secretary Peter Kyle said: "The Secretary (of State) has said that Government needs to demonstrate that Northern Ireland remains a strong and integral part of the United Kingdom in order to restore powersharing.
"A problem for him, though, is that his department still plans to impose immunity for terrorists on Northern Ireland against the wishes of all local parties and all victims' groups there.
"Does he not see the damage this could do to the union?"
Mr Heaton-Harris responded: "Yes, none of the political parties in Northern Ireland are behind this particular Bill, but in great fairness to the Democratic Unionist Party, they have never been behind any sort of amnesty.
"It is a principled position on their part from the Belfast Good Friday Agreement onwards, which I completely understand.
"I don't think I will ever be able to win that argument with them."
He added: "I actually think the Bill that we will present - which will be Article 2 compliant, I truly believe that - will actually go to getting information for a whole host of families that have not had it for well over 25 years."
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