JEREMY Corbyn has been accused of a “shameful abdication of leadership” and of being “not fit to be Prime Minister” after it was suggested he would remain neutral on Brexit during a future referendum campaign.

The attacks by the SNP and Liberal Democrats came after the Labour leader reaffirmed his offer of negotiating a “sensible deal” with Brussels to pull Britain out of the EU, which would involve a new customs union with the EU27, a close single market relationship and guarantees of workers’ rights and environmental protections.

This “credible Leave option” would be put to voters alongside the option of Remain in another public vote.

But when Mr Corbyn was pressed on whether or not he would back Remain or Leave in a Brexit referendum, which he would call as Prime Minister, he repeatedly refused to say.

"My job as Prime Minister would be to deliver that option, that's chosen by the British people," he declared.

"I will credibly present the options and say: 'This is the option, you can Remain, possibly with some reforms to the European Union, or you can Leave, but you will be leaving on these terms which would protect jobs and living standards and trade.'"

Pressed on whether he would remain neutral in the campaign, the Labour leader replied: "As Prime Minister I'm offering the people a choice; the only party that's doing so."

Labour sources denied that in a People’s Vote campaign Mr Corbyn would “stay neutral”. When it was suggested he would emulate Harold Wilson’s “neutral” position during the 1975 referendum, which kept Britain in the EEC, the forerunner of the EU, it was pointed out Mr Wilson's government was in favour of the UK staying in.

As the party’s leadership and members prepare to gather in Brighton this weekend for their annual conference, Brexit will dominate proceedings yet again. A move is expected to force a vote to get the party to swing behind a commitment to campaign for Remain in a second referendum.

The atmosphere could turn tense as a raft of Shadow Cabinet figures, including Tom Watson, John McDonnell, Sir Keir Starmer and Emily Thornberry, have all made clear that however good a deal a future Labour government managed to agree with Brussels, they would vote to keep Britain in the bloc.

Welsh Labour has now emulated Scottish Labour and said it would also campaign for Remain, straining further Mr Corbyn’s position.

What has been dubbed the Labour leader’s equivocation – particularly in light of the Lib Dems’ move to an election posture of revoke – led to his political opponents denouncing what they regard as his “neutral” position.

Nicola Sturgeon tweeted: “'Staying neutral' on Brexit is a shameful abdication of leadership.”

Her SNP colleague Stephen Gethins said: “For the Labour leader to remain neutral on the biggest constitutional crisis facing the UK would be an abdication of duty, given that we already know that any form of Brexit will inflict lasting harm upon the economy and people’s livelihoods.”

The Fife MP, who is the party’s Europe spokesman, added: “There is no such thing as a good Brexit, whether it's red or blue, and economic evidence has shown that thousands of jobs will be lost and our vital public services put at risk. It is little wonder that Labour are miserably trailing in the polls in Scotland.”

Tom Brake for the Lib Dems said: “Jeremy Corbyn is ignoring the lives that are under threat because of Brexit. Effectively, he is saying he will just stand back and watch the mess unfold, demonstrating that he is the worst political leader in British history…He is not fit to be Prime Minister.”