Jeremy Corbyn’s Labour has made clear a new Brexit referendum is possible if parliament rejects Theresa May’s agreement with the EU or if a no-deal exit is looming.

Shadow Brexit secretary Sir Keir Starmer said in that event Labour’s policy would be to keep all “options on the table” as it awaited the outcome of negotiations in Brussels.

The Independent understands several shadow cabinet members take the view that a new referendum could be inevitable, even though Labour’s official position is that the party is not currently calling for one.

It comes as the government released a series of documents making clear the broad impact of a no-deal Brexit – with consequences including everything from new business taxes to higher credit card charges for shoppers.

Sir Keir spoke on BBC Radio 4’s Today programme on Thursday as the number of signatures on the petition for The Independent’s campaign for a Final Say referendum on broke through the 700,000 mark.

Asked whether his party would back a fresh vote on Brexit, he said Labour’s position was first to back a meaningful vote in parliament on the deal Ms May reaches.

He went on: “If that vote is to reject the Article 50 deal, parliament must decide what happens next.

EU warns Brexit will cause disruption with or without a deal

“In those circumstances it seems to me all options should be on the table. So we’ve not called for a vote on the deal. We’ve called for a vote in parliament on the deal.

“But I accept the proposition that if it’s voted down parliament then decides what happens next. And in those circumstances in my experience of the last few years, keep your options on the table, not off the table.”

I accept the proposition that if [the deal is] voted down parliament then decides what happens next. And in those circumstances in my experience of the last few years, keep your options on the table Shadow Brexit secretary Sir Keir Starmer

Party officials said afterwards that Sir Keir’s words did not represent a change in Labour’s official position, but insiders accepted that there is an implication within it that parliament might chose to back a new Brexit referendum.

One told The Independent: “There’s agreement across the shadow cabinet that there has to be a process for parliament to decide what happens if the deal is voted down or if we’re faced with no deal.

“The options are open. That’s the whole meaning of it being a ‘meaningful vote’.”

Labour MPs backing the People’s Vote campaign for a new referendum said Sir Keir’s comments looked like part of a slow shift in the party’s broader stance.

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Chuka Umunna told The Independent: “It’s extremely encouraging to hear what feels like a change in tone from the shadow secretary of state for Brexit.

“Labour members, supporters and voters will certainly be pleased to see the party inching towards committing in full to a people’s vote.”

Meanwhile ex-shadow chancellor Chris Leslie said: “I’m increasingly confident that we are seeing the Labour Party move towards giving the public a final say.

“There’s still a long way to go, party conference will be crucial, let’s hope Keir has the ear of the leader’s office on this.”

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Tens of thousands of people demonstrated in London on Saturday calling for a second vote on Britain's departure from the European Union. / AFP PHOTO / Niklas HALLE'NNIKLAS HALLE'N/AFP/Getty Images NIKLAS HALLE'N AFP/Getty Images People's Vote march – demanding vote on final Brexit deal A young protestor shouts as she takes part in the People's Vote demonstration against Brexit Getty Images People's Vote march – demanding vote on final Brexit deal A woman holds a placard as she joins EU supporters, calling on the government to give Britons a vote on the final Brexit deal, participating in the 'People's Vote' march in central London, Britain June 23, 2018. REUTERS/Henry Nicholls HENRY NICHOLLS Reuters People's Vote march – demanding vote on final Brexit deal epa06833888 Pro-EU demonstrators take part in a People's March anti-Brexit rally in Parliament Square in London, Britain, 23 June 2018. Protesters are calling for a referendum on the final deal. The protest is taking place on the second anniversary of the Brexit referendum. EPA/ANDY RAIN ANDY RAIN EPA People's Vote march – demanding vote on final Brexit deal A protester's pro-EU t-shirt EPA People's Vote march – demanding vote on final Brexit deal epa06833892 A pro-EU demonstrator waves a European Flag during a People's March anti-Brexit rally in Parliament Square in London, Britain, 23 June 2018. Protesters are calling for a referendum on the final deal. The protest is taking place on the second anniversary of the Brexit referendum. EPA/ANDY RAIN ANDY RAIN EPA People's Vote march – demanding vote on final Brexit deal Demonstrators carry banners and flags as they participate in the People's March demanding a People's Vote on the final Brexit deal, in central London on June 23, 2018, the second anniversary of the 2016 referendum. Tens of thousands of people demonstrated in London on Saturday calling for a second vote on Britain's departure from the European Union. / AFP PHOTO / Niklas HALLE'NNIKLAS HALLE'N/AFP/Getty Images NIKLAS HALLE'N AFP/Getty Images People's Vote march – demanding vote on final Brexit deal epa06833960 Tens of thousands of people march through London during a People's March anti-Brexit demonstration in London, Britain, 23 June 2018. Protesters are calling for a referendum on the final deal. The protest is taking place on the second anniversary of the Brexit referendum. EPA/ANDY RAIN ANDY RAIN EPA People's Vote march – demanding vote on final Brexit deal Leader of the Liberal Democrats, Vince Cable speaks during the People's March demanding a People's Vote on the final Brexit deal, in central London on June 23, 2018, the second anniversary of the 2016 referendum. Tens of thousands of people demonstrated in London on Saturday calling for a second vote on Britain's departure from the European Union. / AFP PHOTO / Niklas HALLE'NNIKLAS HALLE'N/AFP/Getty Images NIKLAS HALLE'N AFP/Getty People's Vote march – demanding vote on final Brexit deal epa06833964 A young pro-EU demonstrator takes part in a People's March anti-Brexit rally in Parliament Square in London, Britain, 23 June 2018. Protesters are calling for a referendum on the final deal. The protest is taking place on the second anniversary of the Brexit referendum. EPA/ANDY RAIN ANDY RAIN EPA People's Vote march – demanding vote on final Brexit deal Gina Miller and Caroline Lucas EPA People's Vote march – demanding vote on final Brexit deal epa06834044 Tens of thousands of people march through London during a People's March anti-Brexit demonstration, in London, Britain, 23 June 2018. Protesters are calling for a referendum on the final deal. The protest is taking place on the second anniversary of the Brexit referendum. EPA/ANDY RAIN ANDY RAIN EPA People's Vote march – demanding vote on final Brexit deal epa06833264 Thousands of people march through London during a People's March anti Brexit demonstration in London, Britain, 23 June 2018. Protesters are calling for a referendum on the final deal. The protest is taking place on the second anniversary of the Brexit referendum. EPA/ANDY RAIN ANDY RAIN EPA People's Vote march – demanding vote on final Brexit deal Tens of thousands of people march through London EPA People's Vote march – demanding vote on final Brexit deal epa06833265 Thousands of people march through London during a People's March anti Brexit demonstration in London, Britain, 23 June 2018. Protesters are calling for a referendum on the final deal. The protest is taking place on the second anniversary of the Brexit referendum. EPA/ANDY RAIN ANDY RAIN EPA People's Vote march – demanding vote on final Brexit deal Demonstrators at the People's Vote March Getty People's Vote march – demanding vote on final Brexit deal 'Two months too young to decide on my future' REUTERS People's Vote march – demanding vote on final Brexit deal Crowds taking part in the People's Vote march for a second EU referendum at Trafalgar Square in central London. PRESS ASSOCIATION Photo. Picture date: Saturday June 23, 2018. See PA story POLITICS Brexit. Photo credit should read: John Stillwell/PA Wire John Stillwell PA People's Vote march – demanding vote on final Brexit deal A young girl joins in the march PA People's Vote march – demanding vote on final Brexit deal An EU flag is draped across the statue of Winston Chruchill in Parliament Square REUTERS People's Vote march – demanding vote on final Brexit deal Demonstrators gather prior to the start of the People's March demanding a People's Vote on the final Brexit deal, in central London on June 23, 2018, on the second anniversary of the 2016 referendum. / AFP PHOTO / Niklas HALLE'NNIKLAS HALLE'N/AFP/Getty Images NIKLAS HALLE'N AFP/Getty Images People's Vote march – demanding vote on final Brexit deal Vince Cable MP, Pro-EU campaigner Gina Miller, Tony Robinson and Caroline Lucas MP join with crowds PA People's Vote march – demanding vote on final Brexit deal Crowds gather on Pall Mall in central London, during the People's Vote march for a second EU referendum. PRESS ASSOCIATION Photo. Picture date: Saturday June 23, 2018. See PA story POLITICS Brexit. Photo credit should read: John Stillwell/PA Wire John Stillwell PA People's Vote march – demanding vote on final Brexit deal Crowds gather on Pall Mall PA People's Vote march – demanding vote on final Brexit deal A man resembling Britain's Foreign Secretary Boris Johnson, joins EU supporters Reuters People's Vote march – demanding vote on final Brexit deal EU supporters, calling on the government to give Britons a vote on the final Brexit deal, participate in the 'People's Vote' march in central London, Britain June 23, 2018. REUTERS/Henry Nicholls HENRY NICHOLLS Reuters People's Vote march – demanding vote on final Brexit deal People gather in Trafalgar Square REUTERS People's Vote march – demanding vote on final Brexit deal Pro-EU campaigner Gina Miller and Tony Robinson PA People's Vote march – demanding vote on final Brexit deal EU supporters, calling on the government to give Britons a vote on the final Brexit deal, participate in the 'People's Vote' march REUTERS

Even if Ms May manages to hammer out a deal with the EU, the likelihood of parliament blocking it appears fairly high, with her baseline plans unlikely to meet Labour’s established tests and Tory Brexiteers in open opposition – bringing the question of what happens if the prime minister’s deal fails into sharp focus.

Mr Corbyn would prefer a new election over a referendum, bringing with it the chance of broader power, but leader’s office insiders are said to be increasingly doubtful about the chances of Tory MPs allowing one to happen before 2022.

Shadow cabinet members are going through the same thought process, with several now moving towards the idea that another referendum is likely.

One shadow cabinet source said: “In the end when the government can’t decide, and when parliament can’t decide, it feels like it might be the only way out.”

Pressure to start explicitly pushing for a new vote has been steadily increasing from unions, the Momentum activist group and significant parts of the parliamentary party.

The Independent reported earlier this week that the Co-operative Party – Labour’s sister organisation – which counts three shadow cabinet ministers and eight other frontbenchers among its ranks, is now planning to hold a vote on whether to back a new referendum at its conference in October.

What does a no-deal Brexit mean?

But any movement towards a new vote also carries political danger, with some Labour MPs in Brexit voting areas likely to be unhappy with the idea.

Shadow international trade secretary Barry Gardiner claimed earlier this week that there could be “civil disobedience” in the case of a new referendum.

Mr Gardiner said Remain and Leave campaigners told voters at the 2016 referendum that their decision “will determine the future of our country for the next 40 or 50 years”.