LABOUR heavyweights have accused the party's shadow defence secretary of failing to understand basic science as a furious row over Trident escalated.

Lord Hutton of Furness, the former Labour defence secretary, warned that Emily Thornberry's proposals “belittle our party”.

His party colleague Lord West, a former head of the Navy, said that her claim that drones could some day target submarines was “against the laws of physics”.

He also threatened to resign the Labour whip if it became a unilateralist party.

The anti-Trident Ms Thornberry yesterday briefed Labour’s shadow cabinet on the party's defence review.

Ordered by Labour leader Jeremy Corbyn, a long-time opponent of nuclear weapons, the exercise is seen by many Labour MPs as cover for a campaign by the leadership to overturn Labour's pro-Trident policy.

As the row intensified the GMB union announced its will hold a conference designed to give defence workers their say at the end of this month.

The Defence Secretary Michael Fallon also appeared to capitalise on the dispute within Labour, announcing an extra £200 million funding for the next stage in designing a new generation of nuclear submarines.

Labour also launched a website asking members of the public for their views.

Lord West had earlier rung into BBC Radio 4’s Today programme to gatecrash an interview with Ms Thornberry and accuse her of talking nonsense.

Islington MP Ms Thornberry repeated her warning that drone technology could leave Trident submarines obsolete.

“There are forthcoming generations of drones that can work underseas," she said.

"I've actually met one of the young turks who at the moment is developing these drones, and they are very hopeful that in the next 10 years or so that actually the seas will no longer be opaque."

Lord Hutton denounced that claim as “old science fiction” that had been around since the 1950s.

He called on Labour to “follow the evidence”, which, he said, would mean renewing Trident.

Ms Thornberry also hinted that Labour MPs could abstain on the crunch Commons vote on replacing Trident, due later this year.

She also said ministers were no longer planning to hold a ‘main-gate’ vote.

Instead, she suggested, there would be a vote on the principle of a nuclear deterrent, designed to embarrass Labour.

Shadow home secretary Andy Burnham predicted it could be impossible for Labour to find a compromise on Trident.

He also criticised the so-called “hybrid options” saying “I think most people have found that they just don’t work.”

Mr Corbyn famously suggested that Trident submarines could go to sea with no warheads.

Labour also faced accusations that it wanted to create the most expensive taxi service in the world when it was suggested the party could keep the submarines to ferry service personnel around the world.

Labour MP Madeleine Moon, a member of the Commons defence committee, said she did not think that the review was “honest” and accused Ms Thornberry of not being open-minded about the result.

Paul Kenny, GMB general secretary, said: "It is time that senior politicians in the Labour Party listened to the voice of working people outside Westminster."

Brendan O’Hara MP, the SNP's defence spokesman, said: "Trident is the UK’s ultimate virility symbol – it allows David Cameron to wield what remains of imaginary influence – proving beyond any doubt it is not a military asset – it is a political one."