Theresa May will convene a meeting of her Cabinet after her Brexit plans were dealt a significant blow by the Commons Speaker.

John Bercow scuppered the chance of another Commons vote on the Prime Minister's deal before Thursday's EU summit, leading one minister to warn that the Government faces a "major constitutional crisis".

Mr Bercow ruled that Mrs May cannot bring her EU Withdrawal Agreement back before MPs unless it is substantially different from the package that was decisively defeated last week.

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The Speaker's ruling, announced in an unexpected statement to the Commons, throws a further obstacle in the way of the Prime Minister's scramble to get a deal agreed by the scheduled date of Brexit of March 29.

A Government source said it seems "clear that the Speaker's motive here is to rule out an MV (meaningful vote) this week which also stands in the way of a securing a shorter extension".

"(This) leads you to believe what he really wants is a longer extension, where Parliament will take over the process and force a softer form of Brexit.

"But anyone who thinks that this makes no deal more likely is mistaken - the Speaker wouldn't have done it if it did."

Solicitor General Robert Buckland said the Government was facing a "major constitutional crisis" and Mr Bercow's intervention would have "huge reverberations" for the Brexit process.

He suggested ministers may need to prorogue Parliament and call a new session to get around the ruling.

"There are ways around this," he told BBC News.

"Frankly we could have done without this. Now we have this ruling to deal with, it is clearly going to require a lot of very fast but very deep thought in the hours ahead."

Education minister Nadhim Zahawi warned that the move reduced the chance of Britain leaving the EU, telling BBC Two's Newsnight: "What Speaker Bercow has done has made it much more likely that we don't deliver Brexit."

But Tory former attorney general Dominic Grieve said Mr Bercow was "completely within his rights".

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On Tuesday, Labour leader Jeremy Corbyn will meet leaders of the SNP, Liberal Democrats, Plaid Cymru and Green Party to discuss Brexit.

In a joint statement ahead of the talks, Ian Blackford, Vince Cable, Liz Saville Roberts and Caroline Lucas said: "The UK faces an unprecedented crisis with Brexit, and Westminster remains deeply divided.

"The best and most democratic way forward is to put the decision back to the people in a new vote - with the option to Remain on the ballot paper."

Mr Corbyn will also meet members of the "Norway Plus" group of MPs in a separate meeting on Tuesday.

Meanwhile in Dublin, European Council president Donald Tusk will hold talks with Irish premier Leo Varadkar.