The party's Lord Dodds was speaking after peers backed an amendment from former NI Secretary of State Lord Murphy yesterday . It set out conditions for granting legal immunity to killers as part of reconciliation efforts.

His amendment would give families of victims a say in whether killers are granted immunity from prosecution.

Peers supported his amendment to the Bill 201 to 190, majority 11 – however it was firmly rejected by the Government – which is pushing the bill into law despite strong cross community opposition.

The Northern Ireland Troubles (Legacy and Reconciliation) Bill aims to set up an Independent Commission for Reconciliation and Information Recovery (ICRIR), so the families of victims can find out how their relatives were killed.

As part of this, a limited form of immunity would be offered to those who committed to encourage them to come forward and share information.

Lord Murphy told peers that his amendment “wouldn’t solve the whole difficulty about a bad bill, but it would mean that the involvement of victims’ families and the ability to impose conditions on immunity, including the right to revoke it altogether”. However he acknowledged that the government iswas rejecting his proposed changes.

DUP Lord Dodds backed the amendment. "But as we all know and acknowledge - and it's been shared right across all sides of the house,” he said, “that all the amendments ... do not and cannot rectify the fundamental flaw which is at the heart of this though, and that is providing immunity from prosecution to terrorists."

However he acknowledged that important work was done “to try to mitigate some of the worst aspects of this wretched piece of legislation". Also welcoming the amendment, his party colleague Lord Weir similarly described the bill as "unsalvageable".

Victims Campaigner Kenny Donaldson, director of victims group the South East Fermanagh Foundation objected that the Government’s bill would mean that should a victim/survivor approach the ICRIR body seeking information, “then they have effectively given their consent for the potential of immunity to be given to the perpetrator without having any further stake in the process”. He said Lord Murphy’s amendment should therefore be “enshrined into the law".

Tory grandee Lord Cormack, who as an MP chaired the NI Affairs select committee, said it was “still an unacceptable Bill because it does not command any support outside the Government”.

However, Northern Ireland Office minister Lord Caine rejected the amendment.

"In the Government’s considered view that would critically undermine the effectiveness of these provisions in their principal aim, the recovery of information for the families," he said.

Meanwhile, NI lawyer Kevin Winters has called on the Labour Party to state that it will repeal the bill if it comes to power. He has also asked the Irish government to lodge a legal challenge against it at the European Court of Human Rights.