The Tory manifesto says that “after Brexit we also need to look at the broader aspects of our constitution” and pledges a commission to draw up plans for reform.
Nationalists fear that the Tories have consistently used Brexit as a “smokescreen” for a power grab – planning to take control of powers in devolved areas as they return from Brussels.
The claims were branded “hysterical scaremongering” by the Tories last night.
But it comes after UK Treasury minister Michael Gove suggested earlier this year that Westminster could start spending cash in traditionally devolved areas which he believed would strengthen the Union.
The SNP say this would mean the UK government effectively “bypassing” the Scottish Parliament and directly funding devolved areas.
SNP candidate for Edinburgh East Tommy Sheppard said: “The Tories never supported devolution in the first place – and ever since Brexit they’ve tried to undermine the Scottish Parliament. Now they’re pledging to rip-up the entire way Westminster works and stop themselves being held accountable by the courts.
“This from a Tory leader who was already blocked from unlawfully shutting down parliament to get his way.
“Boris Johnson simply can’t be trusted. The Tories have repeatedly shown that they’re desperate to strip powers from the Scottish Parliament.”
He added: “Make no mistake, if the Tories get a majority they’ll use this vague and open-ended manifesto commitment to rewrite the rules of government.
“Only the SNP can beat the Tories in Scotland stop Boris Johnson getting the majority he craves.
“A vote for the SNP is a vote to escape Brexit, stop Boris Johnson and put Scotland’s future in Scotland’s hands.”
Holyrood is traditionally handed a “block grant” from Westminster to fund devolved areas like the NHS, education and the justice system. It now partially funds from the income tax system which is partially devolved. But the principle has been that the Scottish Government decides how cash is spent in devolved areas.
But Maurice Golden, Scottish Conservative chief whip, dismissed the claims. He said: “This is the kind of hysterical scaremongering we have come to expect from the SNP.
“Voters know that these baseless accusations are designed only to distract from the SNP’s woeful domestic record. Only the Scottish Conservatives can stand up to the SNP, stop indyref2 and get Brexit sorted.”
Gove said in May that a “Treasury rule” means that the UK government “can’t spend money in areas that are devolved”.
“That means when it comes to promoting culture or supporting agriculture and fisheries, the money has to go through the Scottish Government,” he said.
“Once we’ve given the Scottish Government their fair share, the UK government should be able to spend additional money on the basis of need for projects that will strengthen the Union.”