In a speech to mark the 20th anniversary of the Scottish Parliament, he will reject claims of a Brexit “power grab” from the Scottish Government and SNP at Westminster, dismissing them as an “invented grievance”.
“I reject completely the argument put forward by opponents of devolution that it has been crushed by Brexit,” Mr Mundell will say in Edinburgh today.
“I want it to strengthen devolution, and I believe that can and will happen.”
The Scottish Secretary will add that voters “should remain deeply suspicious when opponents of devolution try to present themselves as its champions”.
But SNP depute leader Keith Brown said Mr Mundell was “content with imposing a hard Brexit on Scotland against our will - while making a power grab on areas the Leave campaign pledged would come directly to Holyrood”.
Meanwhile, a Scottish Government report has said Scotland’s economy could be pushed into recession in a no-deal Brexit. The report suggests GDP could fall by up to 7 per cent, with exports dropping by up to 20 per cent, and the value of sterling falling by up to 30 per cent.