Nicola Sturgeon has appealed to Jeremy Corbyn "work together" to topple Theresa May's government after a crucial vote on the prime minister's Brexit deal was abandoned, promising the SNP will support a motion of no confidence if it is tabled by Labour.

The Scottish first minister said delaying the vote was "pathetic cowardice" and vowed that her party would stand with Labour if it follows through with its plan to bring down the government with a confidence vote on Tuesday.

It comes amid chaotic scenes in Westminster, where reports that the meaningful vote was being shelved broke just moments after a Downing Street spokeswoman told reporters it would go ahead.

Ms Sturgeon posted on Twitter: "So @jeremycorbyn - if Labour, as official opposition, lodges motion of no confidence in this incompetent government tomorrow, @theSNP will support & we can then work together to give people the chance to stop Brexit in another vote.

"This shambles can’t go on - so how about it?"

The Labour leader has not responded to her offer but the first minister's comments will ramp up the pressure on the beleaguered prime minister, as she faces one of the biggest challenges of her premiership.

Government sources confirmed that the vote was being pulled in the face of near-certain defeat, with Ms May due to deliver an emergency Brexit statement to MPs on Monday afternoon.

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The last-minute statement is expected to set out her intention to seek further concessions from Brussels to try to win over furious backbenchers.

However the EU immediately poured cold water on the idea, with Irish premier Leo Varadkar warning that the deal cannot be renegotiated.

“The withdrawal agreement, including the Irish backstop is the only agreement on the table. It’s not possible to reopen any aspect of that agreement without reopening all aspects,” Mr Varadkar told reporters in Dublin.

The SNP has thrown its support behind a second referendum on the Brexit deal, in a significant boost to the number of MPs backing a final say vote.