FURIOUS Labour MPs have threatened to quit as Jeremy Corbyn sparked civil war by offering Theresa May a Brexit compromise.

Prominent backbencher Owen Smith said he and “lots of other people” were considering their position after the Labour leader mapped out a Norway-style deal he could sign up to.

In a letter, Mr Corbyn said the “price” of his backing included a permanent UK-wide customs union with the EU, close alignment on the single market and matching Brussels on workers’ rights.

After an outcry, he was forced to write to Labour MPs separately to insist a People’s Vote remained an option – in line with a Brexit strategy agreed at party conference last autumn.

Tory ‘moderates’ such as Oliver Letwin praised the proposal – saying: “This is where cross party consensus can be formed if the PM’s deal fails.”

Fellow ‘Norway’ supporter Nick Boles said: “This takes us a big step closer to a cross-party compromise.”

But pro-EU Labour MPs slammed Mr Corbyn and branded his new ‘tests’ “nonsense”. He stormed: “Labour’s EU policy is all over the place.”

And speaking to the BBC, Owen Smith stormed: “I stood to be a Labour MP with an understanding of what I was doing.

“And at the moment I may be asked by the Labour Party to row in behind a policy decision that they know, and the government knows, is going to make the people I represent poorer.”

The left-leaning bible, New Statesman, named six Labour MPs likely to resign – Gavin Shuker, Angela Smith, Chris Leslie, Chuka Umunna, Luciana Berger and Mike Gapes. All back a second referendum.

Insiders said Thursday’s move by Labour would only fuel speculation Jeremy Corbyn will eventually abstain on the PM’s Brexit deal – allowing it to go through. MPs believe the leadership gave a ‘nod and a wink’ to the 27 Labour MPs who sided with the Government in the crunch Commons showdown at the end of January when Yvette Cooper tried to delay Brexit.

Shadow Brexit Secretary Sir Keir Starmer tried to heal the divide yesterday by insisting a People’s Vote remained an option in Labour’s armoury. And Labour texted MPs to insist it hadn’t been taken off the table.

But Len McCluskey, Unite chief and Jeremy Corbyn’s biggest donor, stirred the fury by “fully endorsing” the Labour leader’s plan. A Unite spokesman said: “We urge all Labour Party members and supporters to get behind them.”