Is Trident a sensible way to spend £20 billion?

The Government will today be accused by rebellious Labour MPs of preparing to squander up to £20bn of taxpayers' money by replacing Trident with a new generation of nuclear weaponry. The cost is equivalent to 800 new city academy schools, 60 medium-sized hospitals or the employment of 20,000 new NHS consultants.

A coalition of independent military analysts, dissident Labour MPs and groups such as Greenpeace and CND argue that replacing Trident will contribute very little to Britain's security in a world that has been transformed since the days of the Cold War. Britain's nuclear deterrent was last modernised in 1980. In a growing insurrection that threatens to split the Labour Party, MPs will argue that any decision to upgrade Britain's nuclear defences would be a disastrous own goal. Party chiefs have gone to extraordinary lengths to prevent a vote on the divisive issue at this evening's meeting of the Parliamentary Labour Party (PLP) which will be addressed by John Reid, the Defence Secretary.

But rebel MPs, spurred on by the belief that they have the private backing of several cabinet ministers, are planning to embarrass the Government by collecting a House of Commons motion underlining the strength of opposition to the move.

One hope is that a final decision could be put off until Mr Blair, who has made clear he favours replacing Trident, steps down as Prime Minister.

The current Trident fleet consists of four submarines carrying up to 48 nuclear warheads - each eight times more powerful than the Hiroshima bomb - mounted on Trident II D5 missiles. As the vessels are due for replacement between 2020 and 2025 and there can be a lead-in time of up to 14 years to develop new weaponry, a decision is due shortly on whether to replace them. The Government says it has to be taken this parliament.

Labour MPs fear the decision has already been taken in Downing Street and worry the "listening exercise" promised by Mr Blair on the subject is cosmetic. They point to a comment by the Prime Minister two weeks ago that he believed the "independent nuclear deterrent" was "an important part of our defence".

There is also anger that ministers have sidestepped demands to give Parliament the chance to vote on the issue.

Backbenchers had hoped to force a vote at tonight's meeting on a motion questioning the "wisdom of spending billions on Trident replacement" .

But internal PLP papers seen by The Independent disclose that the Labour Parliamentary Committee, senior backbenchers who meet the Prime Minister each week, believed it "would be unhelpful to have a vote on the future of Trident" at tonight's PLP meeting. The strong feelings in PLP ranks are, from the Government's point of view, an ominous precursor to other looming rebellions on such issues as education and welfare reforms.

One of the Trident motion's proposers, Gordon Prentice, MP for Pendle, dismissed Mr Blair's call for a debate on Trident as "completely vacuous ". He added: "John Reid will no doubt say that no decision has been taken yet, that the various options haven't been worked through yet."

MPs will argue that no decision needs to be taken for several years and should not be reached until the issues have been fully aired.

Paul Flynn, the Newport West MP, said: "The Cold War has ended and it's possible to discuss these things openly. There's no reason why we should not have a debate and a vote in the Commons on it. Having a new Trident would make the world a more dangerous place. We campaign against nuclear proliferation among other nations and we should lead by example." He said possession of a nuclear arsenal was irrelevant to British forces' main tasks of peacekeeping and humanitarian relief.

The Campaign for Nuclear Disarmament has launched a nationwide petition against the replacement of Trident. It has also circulated among Labour MPs an article by Robin Cook, the late foreign secretary, written weeks before his death, arguing that updating Trident was "against Britain's national interests" and "against our international obligations".

Kate Hudson, the chair of CND said: "We are opposed to any replacement of Trident - no matter what that may be. We need to move towards multi-lateral disarmament."

Possibilities being mooted for a new generation of Trident include the development of multi-role submarines, which can fire both nuclear and conventional missiles, or that new Astute submarines being designed for the Royal Navy could be adapted for nuclear weapons.

A spokesman for the Ministry of Defence said: "There are no official costs or even a list of replacement options for Trident at this time. Any decision on the future of Trident is needed in this parliament and ministers realise the importance of retaining the current Trident provision."

What else could you buy?

* 4 Channel tunnels

* 60 medium-sized hospitals

* 400 new trains for the London Underground

* 715 miles of motorway

* 800 city academies

* 1p cut in basic-rate income tax for five and a half years (or 5.6p cut in basic-rate tax for one year)

* Run the Metropolitan Police for 10 years

* Stage the 2012 Olympic Games 10 times over