Meanwhile, Tom Meadowcroft, the Green candidate in the Tory marginal of Filton and Bradley Stoke in Bristol, has also rejected Green Party calls to support the LibDems and instead backed Labour.

He has quit the contest in the constituency and his party. He attacked the “rank opportunism” behind the Remain pact where the LibDems, Greens and Plaid Cymru agreed to stand aside in 60 seats to give a free run to whichever party had the best chance of returning a Remain MP.

Mr Meadowcroft will instead throw his weight behind the Labour candidate Mhairi Threlfall, a Bristol councillor, in a bid to unseat the sitting Conservative Jack Lopresti.

“To stand down in the neighbouring seat [to give the LibDems a free run] but not mine is rank opportunism and will hurt the very Remain cause that we seem so keen to sacrifice ourselves wholly to,” said Mr Meadowcroft.

He accused Unite to Remain, the umbrella group, of behaving “disgracefully” by giving local activists “almost no detail about the seats that were being discussed in the pact.”

In Pontypridd in south Wales, LibDem candidate Mike Powell has refused a request by the pro-Remain pact to stand aside for Plaid Cymru and vowed to run as an independent. He claimed that members of his party are "extremely unhappy" about how the deal was struck.

He said: "I think that people deserve to have an opportunity to vote for someone who's going to represent the people of Pontypridd, rather than standing to represent a cause to remove Wales from the United Kingdom."

The Greens are also standing aside in three seats in Scotland to give the SNP a clear run in three Tory marginals.