The Deputy Leader of the House of Commons has resigned to oppose the Government's plan to renew Britain's nuclear deterrent.

Nigel Griffiths, Labour MP for Edinburgh South and a Government minister, tendered his resignation to Tony Blair this morning ahead of Wednesday's parliamentary vote on the future of Trident, the UK's submarine-based nuclear weapons system.

"I am resigning with a heavy heart but a clear conscience," he said. "I intend to make a personal statement in the House of Commons to colleagues and it is only right that they hear the reasons first."

Mr Griffiths, deputy to Jack Straw, the Leader of the House, opposes Mr Blair's £20 billion plan to build a new generation of submarines to launch the Trident D5 missiles which Britain leases from America to form its nuclear deterrent.

The current fleet is due to last until 2024, but because the new submarines will take 17 years to design and build, the Government believes that a vote is necessary now.

Mr Griffith's resignation is the second by a Labour MP on the government payroll and illustrates the divisions within the party over the question of Britain's nuclear capabilities. On Saturday, Jim Devine, a parliamentary private secretary to Rose Winterton, a Health Minister, announced his intention to step down and Mr Blair is expected to have to rely on Conservative support to approve the renewal plan.

The Government published its plan to build at least three new V class submarines to carry Britain's nuclear weapons in December. Describing an independent nuclear deterrent as "the ultimate insurance" in international affairs, Mr Blair said: "The one certain thing about our world today is its uncertainty."

But in an attempt to partly pacify the Labour backbenches, which are traditionally opposed to nuclear weapons, the Prime Minister offered to reduce Britain's nuclear arsenal from 200 warheads to 160.

Downing Street declined to comment on Mr Griffith's resignation this morning but the minister, who served in various roles in the Department of Trade and Industry until he was appointed Deputy Leader of the House in 2005, found warm support from fellow Labour rebels.

Jeremy Corbyn, Labour MP for Islington North and a convinced opponent of Trident, said: "I hope other MPs will follow suit and start leading the UK down the path of nuclear disarmament, not re-armament, on Wednesday."

While Alan Mackinnon, chairman of Scottish CND, said: "We welcome the principled stand taken by Griffiths on this crucial issue and we hope his example will be followed by other Labour MPs."

Other anti-nuclear campaigners, including Ewan Aitken, the Labour leader of the Edinburgh Council, said that the resignation of Mr Griffiths, Labour's first MP in the Scottish capital, showed that the rebellion was gaining strength.

Louise Edge, a Greenpeace disarmament spokeswoman, said: "The resignation of Nigel Griffiths just adds to the sense that this decision is being forced on the Labour party by an overbearing executive. We urge all MPs to vote for the cross party amendment to delay the decision and open the door to a serious consultation on this hugely important decision."

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