The revelation came as Labour said it would oppose Government plans to put the Brexit date of 29 March 2019 into law, as MPs began debating the EU Withdrawal Bill clauses in the crucial committee stage in the Commons.
In a column for the Labour List blog, Mr Corbett has suggested that Britain should remain a full member throughout the so-called transition period of at least two years.
His comments have raised concerns that Jeremy Corbyn’s party hopes to ultimately keep Britain in the EU and reverse the historic Brexit vote.
It is understood that Labour hope that Tory Remainer rebels led by Ken Clarke, Dominic Grieve, Nicky Morgan and Anna Soubry will help defeat the Government and force Britain to extend its stay in the EU.
Only the Conservatives can get the best Brexit deal for all parts of the UK, said Tory MP Sunak
Richard Corbett’s comments highlight just how many within Labour are reluctant to deliver the will of the people and frustrate the Brexit process every step of the way
Mr Corbett has previously provoked outrage by leading the Labour MEP group of voting with Euro federalist Guy Verhofstadt’s European Parliament motion calling for trade talks to be delayed until the UK supports a divorce bill.
Unlike the two Tory MEPs who backed the same motion aimed at harming Britain, the Labour group have not been suspended.
Meanwhile, despite promising in their election manifesto to back the referendum vote, Mr Corbyn led his MPs to vote against the first stage of the Withdrawal Bill to implement it.
In his column for Labour List, Mr Corbett, who is a member of Labour’s ruling National Executive Committee (NEC), said that he supported EU claims that the Tory government’s plans for Brexit is “fantasy land”.
Mr Corbett’s comments have raised concerns that Labours hope to keep Britain in the EU
Revealing that Labour wants to keep Britain in the EU for at least the transition period, he said: “Theresa May is signalling that she is prepared to have Britain jump on that day, whatever the circumstances.
“No flexibility to extend negotiations if an agreement is nearly there, but not quite.
“No consideration of the possibility of staying as a member during the transitional period, or part of it, to still have a say on decisions during that period.”
He has previously said on Twitter that he wants to stop Brexit.
On 15 October, he Tweeted: “One would have expected public opinion to rally behind the referendum result, as many politicians have. In fact, it’s moving to #StopBrexit”.
Richard Corbett said on Twitter that he wants to stop Brexit
And in September, during the Labour Party conference, he Tweeted: “Join me Sunday at #StopBrexit rally in #Brighton”.
His column for Labour list also appears to expand on previous comments made by shadow Brexit secretary Sir Keir Starmer who has said he wants to keep the UK under Brussels rule in the single market and customs union.
Sir Keir said: “Labour would seek a transitional deal that maintains the same basic terms that we currently enjoy with the EU.
“That means we would seek to remain in a customs union with the EU and within the single market during this period. It means we would abide by the common rules of both”.
Mr Corbyn also recently revealed that if there is a second referendum he would back Remain.
The hard line Remainer position has emerged from a confused period for Labour which, according to some analysts, has changed its position at least 101 times since the referendum.
Tory MP Rishi Sunak said: “It comes as no surprise Labour are adding to their confusion over Brexit when they’ve set out more than one hundred different positions on it since the EU Referendum.
“Richard Corbett’s comments highlight just how many within Labour are reluctant to deliver the will of the people and frustrate the Brexit process every step of the way.
“Only the Conservatives can get the best Brexit deal for all parts of the United Kingdom, while Labour continue to plot how they can keep us tied to the rules of the EU for the foreseeable future.”
Mr Corbyn recently revealed that if there is a second referendum he would back Remain
Former cabinet minister Owen Paterson said that Labour’s bid to keep Britain under EU rule is “a fantastic once in a generation opportunity” for the Conservative Party to win over traditional Labour voters.
He said: “The Conservatives can now deliver a better standard of living by bringing down the cost of food, clothes and other goods through the freedoms afforded by Brexit which will benefit hard working Labour voters along with everybody else.”
Leading QC Martin Howe has written a paper showing how a transition period threatens to turn Britain into a vassal state of the EU by binding it to its rules and regulations.
He warned: “If Labour;’s gets its way on this it will exacerbate the dangers further and guarantee that we will not be able to enjoy the benefits of Brexit.”
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Meanwhile, ahead of the committee stage of the EU Withdrawal Bill Labour leader Jeremy Corbyn made it clear he opposes “the false arbitrary” Brexit date of 29 March 2019 when the Article 50 two year period runs out.
In the debate itself, shadow Brexit minister Paul Blomfield urged ministers to withdraw the Bill amendment putting the departure date into law describing it as a “gimmick”.
Mr Blomfield said: “If the Government cannot withdraw their amendments and engage in that process with us we cannot support them because of the impact on the economy, on jobs, on livelihoods as we would plunge over the cliff edge.”
He added: “The Government has had months to repair this deeply flawed Bill, they could have come forward with amendments on workers’ rights, on environmental protection, on the charter of fundamental rights, on limiting the scope of delegated powers, but instead they’ve chosen to come to this House with a gimmick on the departure date.
“A gimmick that is about the Prime Minister negotiating with her own party, rather than trying to get a Brexit deal that prioritises jobs, the economy and the livelihoods of our people.”