Southampton's MPs claim more research is needed before a decision is made today on plans for the next generation of nuclear submarines.

Labour MPs Alan Whitehead and John Denham will propose an amendment in the House of Commons which would put off a final decision about the future of Trident until "further consideration of the strategic case, costs, and design of the system" is undertaken.

Sixty MPs are expected to rebel in today's vote and more than 100 MPs have already vowed to seek an open-ended delay to the decision.

The Southampton MPs also believe it is too early to make detailed decisions about Trident's replacement.

But they have chosen to submit their own amendment because, unlike many of the rebels, they support the principle of renewing Britain's nuclear capability and do not want to be mistaken for supporters of unilateral disarmament.

Although their amendment, which is backed by about 15 MPs, is unlikely to be debated, Dr Whitehead said he hoped ministers would accept his concerns and alter their proposals, permitting a further vote before a new weapon system was commissioned.

The Tories have said they will vote for a Trident replacement and the Lib Dems have vowed to vote against the plans.