The SNP's Westminster leader has joined other opposition leaders to write to Theresa May accusing her of "contempt for Parliament" after she delayed the vote on her Brexit deal.

The Prime Minister announced to MPs on Monday that the meaningful vote, which had been scheduled for Tuesday, would be "deferred".

She said the vote was being postponed as the deal was facing a heavy defeat in the Commons, with more than 100 Tory backbenchers set to vote against, along with Labour, the SNP, the Lib Dems and the DUP.

May has travelled to Europe for talks with EU leaders seeking assurances over the contentious Northern Ireland backstop.

However, ahead of meeting the Prime Minister later, European Commission president Jean Claude Juncker said there is "no room for renegotiation whatsoever" on the deal.

Nicola Sturgeon called May's decision to postpone the vote "pathetic cowardice" and is urging Jeremy Corbyn to launch a vote of no confidence against the Tory government.

Her party's Westminster leader Ian Blackford united with Corbyn, Lib Dem leader Vince Cable, Green MP Caroline Lucas and Liz Saville-Roberts of Plaid Cymru to demand clarity from the PM.

They wrote to May asking four key questions:

Blackford said: "Her actions show contempt for Parliament.

"It can't be right that the UK Government can unilaterally alter the arrangements once the House of Commons has agreed on a timetable, without the House being given the opportunity to express its will.

"The meaningful vote must now be rescheduled as soon as possible. As the SNP has made clear, Brexit cannot and must not be a choice between a bad deal and no-deal.

"We believe it is time for the Prime Minister to go and for others to work together to put the decision to the people.

"We must stop the Prime Minister riding roughshod over Parliament in an attempt to preserve her position."

The House of Commons formally found May's government in contempt of Parliament - in an unprecedented step - after it initially refused to publish legal advice on its Brexit deal in full.

But Blackford has also written to the Labour leader - along with Cable, Lucas, and Saville-Roberts - urging him to join them in tabling a no confidence vote in May.

They said there was an "overwhelming" case for a confidence vote to take place now and suggested it would pave the way to a second referendum on EU membership.

It comes ahead of a press conference in London by the People's Vote campaign which is pushing for a second public vote on Brexit.

The MPs wrote to Corbyn: "We believe a motion of no confidence must be brought forward at the earliest possible opportunity, to ensure there is enough time to pursue another course.

"Therefore we want to emphasise again that you will have our full support if you put down a motion of no confidence."

And speaking to STV News on Monday, the First Minister said the UK Government had "completely ceased to govern".

She continued: "It is no longer functioning as a government - that's most obviously the case on Brexit but on a whole range of other issues, this is a government that has ceased to take decisions.

"I think the time is right now for a confidence motion to be launched. If the official opposition do that the SNP will support that.

"Then everybody can look to work together to have another referendum to allow people to decide whether they still want to go ahead with Brexit."

Ahead of meeting May on Tuesday evening, Jean-Claude Juncker said the Withdrawal Agreement struck between the UK and EU was the "only deal possible".

The Prime Minister has already embarked on emergency Brexit talks with European counterparts, starting with Dutch leader Mark Rutte in The Hague.

But Juncker did indicate that "further clarifications and further interpretations" might be possible "without opening the Withdrawal Agreement".

May also plans to meet German Chancellor Angela Merkel before travelling to meet European Council president Donald Tusk at around 4pm, then Juncker shortly after 6pm.

She will then travel on to Brussels, where she is due to meet European Council president Donald Tusk at around 4pm and Mr Juncker at 6.15pm, UK time.