The SNP's Westminster leader has insisted a no deal Brexit would lead the Scottish Government to begin making preparations for a second Scottish independence referendum.

As Theresa May’s hope of a breakthrough with Brussels was fading fast, Ian Blackford also claimed that a Commons majority for a soft EU withdrawal can be formed to stop Britain falling off a hard Brexit cliff-edge.

“We would have a conversation with the people of Scotland and at that point we would be asking the Parliament in Edinburgh to put in place the mechanisms for a second referendum,” explained the Highland MP.

As the clock ticked away towards the December 14/15 European Council, sources at Westminster suggested the Prime Minister would not be travelling to Brussels on Thursday for a meeting with Jean-Claude Juncker, the European Commission President, to seal a deal on the first phase of talks and to ensure that next week the EU27 concluded “sufficient progress” had been made to move the negotiations on to the second phase about trade and transition.

On Monday, the Democratic Unionists vetoed the UK Government’s proposal to maintain “regulatory alignment” on trade between Northern Ireland and the Republic.

After a 24-hour delay the DUP leader Arlene Foster had a brief conversation with Mrs May but said there was “still work to be done in London” with party sources suggesting the row over the Irish border could take “several days” to sort out.

Ruth Davidson, the Scottish Conservative leader, told the PM in no uncertain terms that any separate deal for Northern Ireland would have "unravelled the entire United Kingdom", and the 13 Scottish Conservative MPs, including David Mundell, the Scottish Secretary, would not vote for it.

The UK Government swiftly backtracked. David Davis, the Brexit Secretary, insisted that any regulatory alignment would cover the whole of the UK and not just Northern Ireland while Mrs May pledged at Prime Minister’s Questions that her Government would protect the "constitutional integrity" of the Union.

But Tory Brexiteers, said to include Boris Johnson, the Foreign Secretary, and Michael Gove, the Environment Secretary, are concerned that any UK-wide regulatory alignment would produce a soft Brexit with the country effectively operating to the rules of the single market and customs union.

Nicola Sturgeon seized on such a prospect, tweeting: “This could be the moment for opposition and soft Brexit/remain Tories to force a different, less damaging approach - keep the UK in the single market and customs union. But it needs Labour to get its act together. How about it @jeremycorbyn?”

Mr Blackford confirmed talks with other parties were taking place about securing a soft Brexit majority at Westminster that could derail what he regarded as the Tory Government’s drive for a hard withdrawal and keep the UK in the single market and customs union.

“At some moment there has got to be a wake-up call and parliamentarians across the chamber have got to consider what the impact of a Brexit without a trade deal is going to mean.

“I for one am certainly not of the view that we can take it as read that we are coming out of the single market and the customs union. I would venture in light of the economic harm that will be done to the UK…we can ultimately put together a majority view in the House of Commons[for a soft Brexit].”

The SNP leader added: “We need to encourage not just Labour members and the Labour frontbench but other parliamentarians who share that view as well.”