THE new Scottish Secretary has downplayed the impact of a no-deal Brexit as “bumps along the way”, after Nicola Sturgeon and her Welsh counterpart called it “catastrophic”.

Alister Jack, who replaced David Mundell in Wednesday’s reshuffle, dismissed the warning from the First Ministers as anti-Leave propaganda.

“Well, they’re both Remainers.They would say that,” he told BBC Scotland.

The Dumfries and Galloway MP also flatly ruled out Westminster acceding to a second independence referendum.

After Boris Johnson became Prime Minister, Ms Sturgeon immediately said another vote was “essential” because he had committed himself to Brexit by October 31 “no ifs, no buts”.

Asked if Holyrood should get the power to hold a referendum - which Ms Sturgeon has said she will request again soon - Mr Jack said: “Absolutely not. We decided that in 2014.”

Last week the Office of Budget Responsibility said the UK’s public finances would be £30bn a year worse off even under a “relatively benign” no-deal Brexit with a new tariff regime.

But asked if he believed his own government’s analysis, the Scottish Secretary said: “I don’t think a no-deal Brexit would be seriously damaging if we prepare for it properly.

“I do think there will be bumps along the way. I’m quite realistic about that. I think there are great opportunities for us as a nation on the other side of Brexit.

“I do think there may be some bumps if we end up with no-deal. It’s not my preferred option. But I do think, as the fifth strongest economy in the world, we can do great things.

“As I’ve always found in business, if you’ve got deadlines, and all the options are still on the table, you tend to get deals done if it’s in your interest. And it will be in their interest, with a £100bn trade surplus into the UK, as it will be in our interest to do a deal with them.”

SNP Brexit Secretary Michael Russell called Mr Jack's assessment of a no-deal Brexit as "complete - and dangerous - nonsense".

In 2016, the Fraser of Allander thinktank at Strathclyde University warned a hard Brexit could cost the Scottish economy £8bn in a decade, lead to the loss of 80,000 jobs and decrease wages up to £2,000 per person per year.

Mr Jack also rejected the SNP’s claim that a no-deal would make Mr Johnson’s the last UK Prime Minister as the Union would crack under the strain.

“I don’t believe that for a minute. I believe that we can leave without a deal if we’re well prepared for it.”

He said no-deal preparations would now “start in earnest”, using a £4.2bn fund. “We didn’t get a grip of that in the last regime,” he said.

Mr Jack’s comments followed Mr Sturgeon and Welsh First Minister Mark Drakeford writing a joint letter to Mr Johnson, telling him a no-deal Brexit would be “unconscionable”.

It came as Mr Johnson chaired his first Cabinet to discuss his government’s approach to Brexit, and then made his first appearance at the Commons despatch box at Prime Minister.

Repeating his pledge to take the UK out of the EU on October 31, he said he would “much prefer” to do so with a deal, but was ready to leave without one.

However he set a high bar for the EU to accept, saying he wanted the “abolition” of the Irish backstop, which is anathema in Brussels and Dublin.

In their letter, the two First Ministers said a no-deal crash-out “would be catastrophic for all parts of the UK”.

“It would be unconscionable for a UK Government to contemplate a chaotic no-deal exit, and we urge you to reject this possibility clearly and unambiguously as soon as possible. We are also clear the decision on EU exit must now be put back to the people.”

They said the UK’s “unprecedented constitutional challenges” were also “placing great strain on the relationships between our governments”.

They said a “significant shift” in relations was needed, with London giving the devolved governments in Cardiff and Edinburgh “proper respect”.

They said a review of intergovernmental relations set up by Theresa May must be completed to create “more robust machinery for working together on the basis of greater equality”.

The SNP seized on a YouGov poll about British voter opinions.

Although the Scottish part of the 1655 sample was 142 people, Mr Johnson’s ratings were consistently and strikingly worse in Scotland than elsewhere.

Scottish voters were far more likely to have an unfavourable opinion of him, to distrust him, to think he was incompetent, and to not believe he could achieve Brexit by Hallowe’en.

SNP depute leader Keith Brown said: “People across Scotland are in no doubt – Boris Johnson is incompetent, untrustworthy and completely out of touch. We have absolutely no faith that the Prime Minister can protect Scotland’s interests. He’s just appointed the most right wing, hard-line Cabinet imaginable - and he’s gearing up to crash us out the EU with No Deal.

“It is becoming increasingly clear why Scotland’s interests simply cannot be protected by Westminster. Scotland must have the choice to choose a better future with independence.”

Aberdeen Tory MP Ross Thomson said reports of the PM’s unpopularity in Scotland were a “false narrative”.