David Mundell has said the SNP are supporting a no-deal Brexit by failing to endorse the Withdrawal Agreement negotiated by Theresa May.
The Scottish Secretary had written to SNP Westminster leader Ian Blackford, who previously called on Mr Mundell to back an extension of Article 50 in order to avoid a no-deal scenario.
Mr Blackford’s letter also urged Mr Mundell to resign if he does not oppose a no-deal Brexit with the UK due to leave the European Union on March 29.
The exchange came as the Prime Minister ruled out a “meaningful vote” on Brexit in the Commons this week, insisting one would be held by March 12.
Mr Mundell said her proposals offered “a sensible, pragmatic way forward” and told Mr Blackford: “By failing to endorse the Withdrawal Agreement negotiated by the Prime Minister, you and your party are supporting a no-deal Brexit.
“I agree with you that outcome would have very serious economic consequences for Scotland and the UK, so I would urge you to reconsider.”
He added: “The deal negotiated by the Prime Minister achieves the broad objectives outlined in the Scottish Government’s Scotland’s Place in Europe papers.
“It provides an implementation period that avoids a sudden ‘cliff edge’, offers businesses the certainty they require and allows time for our future trading relationship with the EU to be negotiated… It also respects the result of the UK-wide referendum in 2016.
“MPs who rejected the deal would be held responsible for delivering a no-deal Brexit outcome. In my view, they would not be forgiven quickly by the people of Scotland.
“Your approach is as damaging as it is cynical. In the coming days, you and your colleagues will have the opportunity to do what is right for the people you represent: to support our departure from the EU with a deal.
“I would urge you to work in Scotland’s interests, not your party’s.”
The SNP MP had initially said: “Crashing out of the EU with either Theresa May’s bad deal, or with no deal at all, is a false choice that would be disastrous for Scotland – destroying jobs, damaging living standards, and leaving the whole country poorer and worse off.”
It was a line reiterated by the Scottish First Minister on Sunday afternoon, who added to the dismay of business leaders at the latest Brexit delay.
Nicola Sturgeon said on Twitter: “If the House of Commons fails to seize control of the #Brexit process this week to force a delay, it will be as culpable as the PM/UK government when UK crashes out at the end of March with either no deal or the PM’s very bad deal.”
Mr Blackford also referred in his letter to a report published on Thursday by Scotland’s top economic adviser which suggested a no-deal scenario could result in a recession worse than 2008.
A UK Government source said: “This is gross hypocrisy from the SNP. The SNP are doing their best to bring about a no-deal, despite knowing the damage that would do to Scotland.
“They are only interested in their own divisive, nationalist agenda, not what is best for Scotland.”