NICOLA Sturgeon has warned the “chaos” in the Tory Government has raised the prospect of a cliff-edge Brexit.

The First Minister gave her assessment after arch-Brexiteers Boris Johnson and David Davis stormed out of the Government on Monday in protest at the blueprint for future EU relations put forward by the Prime Minister.

Junior minister Steve Baker and parliamentary aides Chris Green and Conor Burns also quit. Former foreign secretary Johnson said the plan, which proposed closer alignment than previously suggested between the UK and EU over the trade of goods, would leave Britain as “a colony” of Brussels. The former Brexit secretary said he could not sell the proposals to MPs or the EU.

Interviewed on BBC Radio 4 Today programme yesterday morning, Sturgeon indicated the resignations heightened the prospect of a no-deal scenario.

“Of course a hard Brexit is always a prospect,” she said. “I think the chaos at the heart of the UK Government does raise the prospect that we will go over the cliff edge.”

The First Minster also made clear that the SNP will not back May’s plan – drawn up at Chequers last Friday – as it excluded services from alignment with EU rules.

Asked if she would support the new proposal, Sturgeon said: “Not on the basis of the plan as it stands.

“I described it at the weekend as a step forward in the sense there appears to be more realism ... [but it] remains to be seen if it is acceptable to the EU. It still seems to be cherrypicking from the four freedoms. It looks horrendously complicated and of course it excludes services which make up almost 80% of the Scottish economy and the UK’s for that matter.”

Sturgeon added it was also “highly questionable” if the Chequers plan would get majority Commons support. She said a plan supporting single market and customs union membership stood “a realistic chance of commanding a majority ... as well as being the right thing in the interests of the economy”.

Asked about Scottish Tory leader Ruth Davidson’s claim that May’s proposals were right for the economy, Sturgeon said Davidson would argue whatever May told her to. She went on to underline the importance of immigration to the economy, which the PM’s proposals would limit.

Meanwhile, a survey revealed UK voters are shifting their views towards immigration – hostility to which was a driver in the vote to leave the EU. Some 17% of respondents to the British Social Attitudes survey thought immigrants had a negative impact on the economy and 23% thought they undermined Britain’s cultural life. In 2011 about 40% thought immigrants were bad for the economy or British cultural life.

Tweeting a link to an article on the survey, European Parliament chief Brexit Guy Verhofstadt said: “Confirms what many of us on the continent knew, that Brexit aside, Britain is one of the most tolerant & welcoming countries in Europe.

“If only more British politicians were willing to explain the positive effects of migration instead of leaving it to those exploiting fears.”