Left rallies its forces for Commons rebellion on Trident

Labour MPs are calling for an emergency party conference to debate whether to back the decision to replace Britain's independent nuclear deterrent.

Members of the left-wing Socialist Campaign Group of MPs expressed opposition to any move to replace the Trident system, and the Liberal Democrats said they would cut Britain's nuclear arsenal by half and put off a decision on a replacement for nearly a decade.

John McDonnell, chairman of the Campaign Group, said: "If such a decision is forced through on the whim of the Prime Minister and on the back of Tory votes, it could split the party for a generation." Jon Cruddas, a contender for Labour's deputy leadership, said he was unconvinced of the need to replace Trident. "I want to see actually a debate across the party about it, because I think this is so critical that the party has to be involved," he said.

Sir Menzies Campbell, the Liberal Democrat leader, said: "Cutting our stockpile in half would send a strong signal that nuclear disarmament is back on the international agenda and that Britain is prepared to act first."

Tony Blair will make a personal statement to the Commons on Monday to publish a White Paper on the nuclear deterrent.