Former Labour leader Neil Kinnock has warned Jeremy Corbyn he is about to commit a “serious evasion of duty” by refusing to back a plan to keep Britain in the single market.

Writing exclusively for The Independent, Lord Kinnock said his refusal would see the party expose the working people it is supposed to protect, to the “rockslide” of hard Brexit.

He dismissed Mr Corbyn’s claims that the single market would restrict the UK’s ability to intervene in British industry as being part of an “infantile leftist illusion”.

Then in comments that will be seen as an incitement for MPs to rebel against Mr Corbyn’s stance in a pending vote, he argued that while he values loyalty, it is a “virtue that, in excess, fills graveyards”.

His intervention comes amid the deepening internal row about Labour’s approach to Brexit, which has already seen a mass rebellion in the House of Lords this week.

Peers defied Mr Corbyn’s will and backed a proposal to keep the UK in European Economic Area, meaning it will now be voted on in the Commons where Tory rebels say they are strong enough to make it law as long as Labour also backs it.

But with Mr Corbyn so far refusing, Lord Kinnock wrote: “It would be a serious evasion of duty if Labour did not seize this chance to protect our country from the rockslide of ‘hard’ Brexit.”

He added: “Labour must make this challenge.

“By supporting continued EEA participation we can end the prime minister’s deference to the cliff-edge kamikaze squad and force her, or her successor, into the pragmatic patriotism of putting country before party.”

The peer, who led his party from 1983 until 1992, joined 82 other Labour figures in the House of Lords this week in dismissing his leader’s call to abstain on a motion proposing to keep the UK in the EEA.

Instead, their support saw the motion approved, now to be sent back to the Commons for a vote, where Tory backbenchers say they have up to 15 rebels willing to back it, and force Theresa May to keep Britain in the single market.

As the Labour leadership is poised to whip MPs against the plan, Lord Kinnock wrote: “I do not break the whip lightly.

“I respect our Labour leadership in the Lords and I value loyalty. But I have also said that the virtue, in excess, fills graveyards.

“In this case, not continuing in the EEA would mean endangering – sacrificing – thousands of skilled and decently paid jobs and, with them, the life chances of countless families and communities.”

Earlier this week Mr Corbyn’s office reiterated arguments previously set out by the leader that remaining in the single market as it stands would hamper his interventionist industrial agenda if he won power.

In particular, Mr Corbyn has concerns about what he sees as restrictive state aid rules and regulations that might interfere with his plans to reverse the privatization of public services.

But Lord Kinnock rubbished the claims as being “based on falsehood”, adding: “Neither the EEA nor the EU are part of the socialist superstate of neocon delusion, or of the global capitalist adventure playground of infantile leftist illusion.

“The EEA is a mixed-economy agreement of 31 democracies ‘to promote continuous and balanced strengthening of trade and economic relations between the contracting parties with equal conditions of competition and the respect of the same rules’.

“None of that prevents public ownership, social initiative, improving tax justice, promoting employment or advancing the welfare state.”

Earlier this week five Labour MPs in the Northeast wrote a joint-article in The Independent warning that failure to back the UK staying in the single market would devastate family living standards in their region.

Phil Wilson, Paul Williams, Bridget Phillipson, Anna Turley and Catherine McKinnell said new facts are now emerging about Brexit, that create a critical need for a new referendum.

Ex-shadow cabinet minister Owen Smith was sacked from the Labour front bench earlier this year for backing another referendum, while shadow business secretary Barry Gardiner managed to keep his job despite saying a key element of Labour’s approach was “bollocks”.

​MPs Clive Lewis and Rachael Maskell have both called for a new referendum and, along with Dawn Butler and Tulip Siddiq, quit jobs on the front bench last year over the party’s insistence that they vote to trigger Article 50 and leave the EU.

Welsh MP Geraint Davies has previously called for a new referendum, while London MP Gareth Thomas also demanded a “people’s vote” in the Commons on Wednesday.

Labour’s Northern Irish sister party, the SDLP, wrote to all of Mr Corbyn’s MPs on Thursday warning them Labour’s current approach will not prevent a hard border in Northern Ireland and will risk the Good Friday Agreement.

Ms May’s cabinet is also deeply divided on Brexit, with the issue of what kind of customs relations to adopt set to be discussed again at a meeting of senior ministers on Tuesday.

Foreign secretary Boris Johnson has denied being disloyal, despite calling the option of a “customs partnership”, said to be preferred by Ms May, a “crazy” idea. Business secretary Greg Clark has said thousands of jobs could be put at risk if the UK does not implement it.