A no-deal Brexit would be “catastrophic” for Scotland, according to David Mundell.
The Scottish Secretary said he would not view such a scenario as being acceptable for the country.
Prime Minister Theresa May’s Brexit plans were last week signed off by her Cabinet, although several members subsequently resigned, including Brexit Secretary Dominic Raab.
Mr Mundell branded Mr Raab a “carpetbagger” whose resignation was “about manoeuvring and leadership”.
Conservative MP Ross Thomson urged Mr Mundell to join other senior Conservatives in quitting the Cabinet, telling him “no unionist” could support the proposals.
I believe it would be a fundamental threat to the continuation of the United KingdomDavid Mundell
However, the Secretary of State for Scotland indicated that despite reservations about the deal, it is still better than current alternatives.
He told BBC Scotland: “I’m supporting the deal because I believe a no-deal outcome would be catastrophic for Scotland.
“I believe it would be a fundamental threat to the continuation of the United Kingdom and therefore in the round you have to weigh up all the issues.
“These are difficult and complex judgments but I’m not prepared to countenance a no-deal outcome for Scotland.
“Everyone is clear it’s not a perfect deal. It’s not as bad a deal as characterised. It contains many positive elements in relation to the rights of EU citizens.
“Going forward, it contains this hugely important prospect for Scottish businesses for being able to trade in the EU without tariffs, without quotas – that’s the number one thing that businesses have said that they want.”
First Minister Nicola Sturgeon has said SNP MPs in Westminster will vote against the deal when it is put forward in the House of Commons.
Mr Mundell suggested the reasons for doing so are linked to campaigning for a second Scottish independence referendum.
He said: “That’s why Nicola Sturgeon is so keen on it, that’s why she’s mandating her MPs to vote for a no-deal Brexit, because she understands that the chaos and disruption that a no-deal Brexit would bring would be the best recruiting base for her independence referendum.”
SNP MSP Tom Arthur suggested Mr Mundell was refusing to put Scotland’s interests ahead of the interests of his party.
He said: “David Mundell makes himself look and sound more ridiculous with every day that passes.
“First he indicated he would resign if Northern Ireland was given special treatment, then he reportedly voiced concerns about the proposed deal while in Cabinet and now he has admitted Theresa May’s plan will leave Scotland worse off.
“But still he clings to office, without a shred of principle or credibility.
“It seems there is literally nothing that can happen that would lead David Mundell to put Scotland’s interests before the Tory party’s interests.
“He is quite clearly the Cabinet’s man in Scotland rather than Scotland’s man in the Cabinet – and his position is now utterly untenable.”
Scottish Liberal Democrat leader Willie Rennie called Mr Mundell’s comments “unconvincing” and insisted there must be another vote on Brexit.
He said: “The Scottish Secretary can’t bring himself to say the Prime Minister’s deal will make life better for people in Scotland and that’s because it won’t.
“Tearing ourselves out of Europe will hit every single Scottish household.
“People across the country watched the chaos of last week unfold and Conservative divisions deepen.
“Nobody is fooled by David Mundell’s unconvincing claim that this is the only way forward.
“Those who favour a people’s vote now make up the biggest cohesive bloc in British politics.
“Hundreds of thousands of people have taken to the streets demanding the chance to avoid a big Brexit blackhole.
“Tory arrogance has taken us this far. People deserve better than to be marched into a terrible deal that will hurt their finances.
“The Brexit decision needs to go back to the people.”
Scottish Labour MP Lesley Laird said: “Theresa May once believed that no deal was better than a bad deal.
“Now David Mundell is saying the exact opposite yet sees no conflict with his position in Cabinet.
“To back this bad deal as the only alternative to a no-deal Brexit is to accept a false choice.
“Instead of leadership from Theresa May’s government we are getting brinkmanship.
“Parliament must be given a meaningful vote on the half-baked mess that Theresa May has brought back from Brussels and when, as appears likely, it is voted down, it is Parliament that must set out the next steps towards delivering a deal which delivers on the promises made to voters at the outset.”
She added: “It was embarrassing to hear Mr Mundell unable to make any positive case for supporting Theresa May’s deal this morning.
“It is clear the majority of his Scottish Tory colleagues are also unconvinced.
“They should all now finally stand up for Scotland and reject this broken deal.
“Scotland deserves better than Tory ministers and MPs who slavishly put party first and the people second.
“Mr Mundell must resign if he is to retain even a scrap of credibility on this.”