Andrew Mackay, the Conservative Northern Ireland spokesman, issued a statement urging the Government to accept amendments for today's committee stage of the legislation, ensuring a tight linkage between the decommissioning of weapons and the release of prisoners.
"It must be a precondition that decommissioning is taking place before prisoners are released," he said. "If the Government refuses to accept the amendments, the people of Northern Ireland will feel cruelly let down."
There was little sign of a Government climb-down being offered yesterday.
A spokesman for the Northern Ireland Office said that while ministers would show "flexibility" towards the amendments, tabled in conjunction with the Ulster Unionists, the Good Friday agreement could not be rewritten, and the legislation already embodied the Prime Minister's pledges on decommissioning and prisoner release. The bottom line for ministers, the spokesman added, hinged on the continuation of a complete and unequivocal cease-fire.
Michael Howard, shadow foreign affairs spokesman, told GMTV's Sunday Programme: "Of course we desperately want to see peace throughout Northern Ireland, but we think that assurances were given about decommissioning and we think there should be links, as the Prime Minister said there would be, between decommissioning and the release of prisoners.
"That's why we've put down amendments to secure that link and if those amendments are not accepted, then I think we will vote against this Bill on third reading on Thursday."
A Conservative vote against the Government on the amendments tonight, and against the whole Bill on Thursday, would be the first concrete divide between government and opposition on Northern Ireland for many years.
While the Opposition showed little enthusiasm for the groundwork leading up to the Good Friday agreement, they have always pulled up short of outright attack - and they are undoubtedly taking a strong political risk if they undermine the united British approach, and contribute towards a breakdown in the process.
But Mr Howard said yesterday that the concept of releasing recently convicted terrorist prisoners was very difficult for many people, and many victims and their families.
"If we are to accept that," he said, "and we are prepared to accept it in the cause of peace, and in the cause of an agreement on bringing violence to an end in Northern Ireland, then we really must see some progress on decommissioning.
"We can't simply release all these prisoners back to the bombs and the guns and the bullets which they have used with such terrible effect in the past."Reuse content