Shadow Wales secretary Jo Stevens, pictured, said leaving the EU is a 'terrible mistake' and handed in her resignation letter to Mr Corbyn this afternoon

Labour veered towards all-out civil war today after a second frontbencher quit over Jeremy Corbyn's decision to order all MPs to vote for Brexit.

In her resignation letter Shadow Wales secretary Jo Stevens said she was 'a passionate European' who believes leaving the EU is a 'terrible mistake' and will vote against the Government's bill to start the Brexit process.

The Labour leader is braced for at least three more resignations after announcing he will impose a three-line whip on MPs to vote in favour of triggering Article 50, which will notify Brussels of our intention to leave.

On yet another day of Labour chaos over Brexit, Mr Corbyn's office confirmed that any frontbench MP who defies his three-line whip on the vote will be sacked.

A host of other shadow ministers have vowed to rebel and vote against Brexit.

Earlier today it was unclear whether Mr Corbyn would sack the rebels for breaking the three-line whip - a move that is normal in order to maintain party discipline.

But a source close to the Labour leader confirmed that 'usual expectations for a three-line whip apply'.

Humiliatingly for Mr Corbyn, two of the rebels are shadow whips, whose jobs are to enforce party discipline.

WHO'S IN AND WHO'S OUT? Two Labour MPs have so far quit Jeremy Corbyn's frontbench over his decision to impose a three-line whip on backing Brexit, but more are expected to follow. Several shadow cabinet ministers close to Mr Corbyn have performed U-turns and confirmed they will vote in favour of triggering Article 50 despite previously vowing to oppose it. DEFINITELY OUT: Jo Stevens quit as shadow Wales Secretary today, saying she 'cannot reconcile my overwhelming view' that leaving the EU is a 'terrible mistake'. Tulip Siddiq resigned from her junior shadow ministerial job in charge of Labour's early years policy last night. PROBABLY OUT: Daniel Zeichner, MP for Cambridge, is expected to quit from his role as a shadow transport minister after vowing to vote against Article 50. Jeff Smith, MP for Manchester Withington and a shadow whip, said he would echo his Remain constituency's views and vote against Brexit. Thangam Debbonaire, Bristol West MP and another whip, said she would 'deal with the consequences' of defying Mr Corbyn and opposing the Article 50 bill. Catherine West, a shadow foreign minister and ally of Mr Corbyn, is another considering her position. DEFINITELY STAYING (AFTER SAYING THEY WOULD VOTE AGAINST) Clive Lewis, shadow business secretary, a close ally of Mr Corbyn, said he had decided not to defy the whip, despite signalling last week that he would vote against triggering Article 50. Cat Smith, another shadow cabinet minister close to the leader, confirmed on Twitter she will vote in favour of triggering Article 50 amid reports she was set to quit. Dawn Butler, shadow cabinet minister for diverse communities, was the latest to confirm she will back the bill despite saying last year she could not support it. Advertisement

And today shadow home secretary Diane Abbott, a confidant of the veteran left-winger, caused more confusion after she said the Labour leadership would 'review our position' if it failed to win key concessions on the Article 50 bill.

A party spokesperson insisted her comments did not mean Labour would ever vote against Brexit.

'We absolutely won't vote against it... we will not frustrate the passage of the bill,' a spokesperson said.

Labour has tabled no fewer than seven amendments to the bill, including one that would force Mrs May to reopen negotiations with Brussels if MPs do not like her deal with the EU - effectively delaying Brexit indefinitely.

In what would be a humiliating move for Mr Corbyn, two of his whips - whose jobs are to enforce party discipline - have vowed to defy his order to back the Article 50 bill.

He has already suffered one resignation after Tulip Siddiq quit the frontbench because she 'cannot reconcile myself' to backing Brexit.

Explaining Labour's position on the Article 50 bill, Ms Abbott told the Today programme: 'This is a question of opening the process we will seek to amend and if we are not able to get any of our amendments through clearly we will have to review our position.

'What happens to people that vote not to trigger will be managed by the whips but the leadership has a lot of sympathy for people in heavily Remain constituencies who find themselves in difficulty.'

Jeff Smith, MP for Manchester Withington and a shadow whip, said he would echo his Remain constituency's views and vote against Brexit, while Bristol West MP Thangam Debbonaire also said she would defy the whip.

The rebels have signalled they could even stay in Mr Corbyn's frontbench despite defying a three-line whip, which would be an unprecedented move, particularly for whips.

It highlights Labour's chaotic position on Brexit, which has torn the party further apart over whether they should respect the referendum result or fight to keep Britain in the EU.

The third frontbencher who confirmed he would rebel against Mr Corbyn is Daniel Zeichner, a shadow transport minister and MP for Cambridge.

He told the Cambridge Evening News it is a 'very straight forward decision for me' to vote against Article 50 and suggested he could even stay on the frontbench.

Jeremy Corbyn, pictured at a Holocaust Memorial Day event in Islington, north London today, confirmed he will impose a three-line whip on the upcoming Commons vote on supporting the Government's Article 50 bill, which will notify Brussels of our intention to leave the EU

Tulip Siddiq, pictured left has confirmed she will resign from Jeremy Corbyn's frontbench if he goes ahead with imposing a three-line whip for the vote on triggering Article 50. Cambridge MP Daniel Zeichner, right, a shadow transport minister, is also expected to resign

In her resignation letter, posted on her Twitter feed, Shadow Wales secretary Jo Stevens said she was 'a passionate European' who believes leaving the EU is a 'terrible mistake' and will vote against the Government's bill to start the Brexit process

'It's my strongly held personal position, and I represent three quarters of the people of Cambridge,' he said.

'I have every respect for those in Cambridge who voted to leave but my job in this city is to represent the people of Cambridge.

'BREXIT IS A TERRIBLE MISTAKE': JO STEVENS RESIGNATION LETTER Jo Stevens became the first shadow cabinet minister to quit over Jeremy Corbyn's decision to impose a three-line whip on backing the Article 50 bill that will notify the EU of our intention to leave. In her resignation letter to Mr Corbyn she wrote: 'I accept the referendum result is to leave. I also accept that the parliamentary numbers are such that Article 50 will be triggered and we will leave the EU. 'But I believe that leaving is a terrible mistake and I cannot reconcile my overwhelming view that to endorse the step that will make exit inevitable is wrong. 'I expect this to be the most important vote I will ever cast as an MP and for me it is a clear issue of principle and conscience.' She added: 'When I vote I will be representing my constituents, a great many of whom, including a great many Labour party members and voters, have strongly urged me to vote in this way. 'That is why, in shadow cabinet, I argued against the imposition of a three-line whip.' 'It is with deep regret that this inevitably means I must resign from the shadow cabinet. 'It has been an honour and a privilege to serve as your shadow secretary of state for Wales, the country where I was born, bred, work and live.' Advertisement

'I've had perfectly civilised conversations [with the Labour leadership]. They know my position and they understand exactly why I'm doing what I'm doing and it's for them to decide what to do next.'

Confirming he would also vote against Brexit, Mr Smith said: 'My constituents voted strongly for remain and I think it's important to represent their view.'

And Ms Debbonaire told Business Insider she would 'deal with the consequences' after rebelling against the Labour leadership.

Ms Siddiq, 34, whose Hampstead and Kilburn constituency backed Remain, became the first to quit the frontbench last night.

In her resignation letter she wrote: 'I feel that the most effective place for me to counter Theresa May's hard Brexit is from the backbenches.'

More frontbenchers have signalled they will also quit Mr Corbyn's shadow ministerial team.

Dawn Butler is said to be considering resigning, as well as junior shadow ministers Catherine West, a shadow foreign minister.

But shadow business secretary Clive Lewis, a close ally of Mr Corbyn, said he had decided not to defy the whip, despite signalling last week that he would vote against triggering Article 50.

Amid speculation that he would inflict a humiliating resignation on Mr Corbyn, Mr Lewis issued a statement this afternoon explaining that he will 'join my colleagues in voting for the bill'.

The latest Labour chaos over Brexit came after Commons Leader David Lidington today tabled the legislation that will finally trigger Article 50.

The 'notification of withdrawal' Bill will empower ministers formally to tell the EU we want to quit.

After a week of confusion over Labour's position on the vote, Mr Corbyn finally revealed his decision to order MPs to support the Government's Article 50 bill.

The text will be at the heart of the impending 'hand to hand combat' in parliament - sparked by the Supreme Court's ruling that Theresa May cannot use executive powers to invoke Brexit

The Leader of the Commons, David Lidington, announced today that there will be five days of debate on the Bill

He told Sky News: 'It will be a clear decision that we want all of our MPs to support the article 50 vote when it comes up next week.'

Confirming it will be a three-line whip, he said: 'It's clearly a three-line whip. It is a vote on the article 50... We will put out a statement today to our members that we want them to vote for article 50.'

WHY THE BREXIT WHITE PAPER COULD END UP IN COURT White Papers are routinely used by ministers to set out policy ideas in detail ahead of legislation. The documents, which can run to hundreds of pages, allow MPs, lobbying groups and others to comment before policy becomes law. Critics have pointed out that previous prime ministers have published a White Paper in advance of every new EU treaty, setting out broad negotiating priorities. The document ahead of the Lisbon Treaty in 2007, for example, ran to 42 pages. However, White Papers have sometimes formed the basis for judicial reviews – leading to protracted legal action in the courts. Theresa May has so far resisted publishing a paper on Brexit over concern it could tie her hands during negotiations with Brussels and open the door to legal challenges. She has backed down over fears of a Commons defeat. Sources suggest the Brexit White Paper is likely to offer little more than the 12-point plan for leaving the EU that Mrs May set out last week. Advertisement

Be he added: 'I fully understand the pressures and issues that members are under, those who represent leave constituencies and those who represent remain constituencies.

'Labour is in the almost unique position of having MPs representing constituencies in both directions and very strongly in both directions.

'I say to everyone unite around the important issues of jobs, economy, security, rights, justice, those issues, and we will frame that relationship with Europe in the future, outside the Europebut in concert with friends, whether those countries are in the EU or outside the EU.

'That's the message we're putting out. And I'm asking all of our MPs not to block article 50 but to make sure it goes through next week.'

John Mills, who used to be one of Labour's biggest donors until he withdrew his support for the party under Mr Corbyn and chaired the Labour Leave campaign during the referendum, told frontbenchers they would be 'highlighting just how out of touch the party are with their traditional supporters' if they voted against Brexit.

He said: 'The fact that Labour frontbenchers are even contemplating voting against the triggering of Article 50 highlights just how out of touch the Party are with their traditional supporters.

'70 per cent of Labour-held constituencies voted to leave in the referendum in June 2016. They voted to leave because they felt that globalisation has created huge disparities in equality and opportunity between the metropolitan elite in cities like London and Manchester, and the UK's erstwhile heartlands.

'There is now an existential crisis facing the Labour Party. If we continue down this road, and MPs oppose the will of the British people in favour of Brexit, there is no plausible way in which I can see the Party forming a government in 2020.'