John Swinney issued the rallying call as he claimed Boris Johnson secretly wants to take back powers from devolved parliaments and have “unfettered Westminster control on Scotland”.
Addressing the SNP conference on Saturday, Mr Swinney argued the sleaze scandal engulfing the Conservative Party shows Westminster is “rotten to the core”.
Insisting “the only way to keep the gains of devolution is by becoming independent”, Mr Swinney suggested the Conservatives had “lost all moral authority to hold the highest offices in the land”.
In a grotesque irony, the Tories are using something that the people of Scotland voted overwhelmingly against - Brexit - to undermine something they voted overwhelmingly for - the Scottish Parliament
John Swinney, Deputy First Minister
Referencing the Owen Paterson case where the Prime Minister attempted to block his suspension for breaking rules on paid lobbying, Mr Swinney said: “The Tories have rewritten the definitions of cronyism and corruption.
“And when they are caught bang to rights by an independent investigation, they just rewrite the rule-book as well.”
Accusing the Conservatives of having “contempt for Scotland’s democratic Parliament”, he suggested decisions made at Holyrood “can be routinely undermined at a whim by the Tories”.
In a virtual speech to the conference, Mr Swinney said: “All of us who care so deeply about the Scottish Parliament and its role in Scottish public life need to stand up and be counted before it is too late.
“We are now seeing a concerted attack on our Parliament, from the very people who fought tooth and nail against it being established in the first place.
“In a grotesque irony, the Tories are using something that the people of Scotland voted overwhelmingly against – Brexit – to undermine something they voted overwhelmingly for – the Scottish Parliament.
“Through the Internal Market Act, the Tories have given themselves unfettered power to decide the rules of the internal market – and to completely ignore the devolution settlement if they want to.”
Claiming the Prime Minister wishes to reverse devolution, Mr Swinney said: “There will be no sudden big bang moment, Boris Johnson is not going to stand up and announce to the cheering Tory faithful that he is dismantling the devolution settlement – much as I am sure he would like to.
“But make no mistake – piece by piece, devolution is quietly being filleted, hollowed out from the inside by a Tory Party which has always opposed the idea of anything other than unfettered Westminster control on Scotland.”
Mr Swinney’s comments were dismissed by a UK Government spokeswoman who said: “This is simply nonsense.
“The Internal Market Bill ensures that vital trade can continue seamlessly between all four corners of the UK.
“Now more than ever, people in Scotland want to see the UK and Scottish governments working together to protect lives and livelihoods.
“The pandemic, and our collective response – from the furlough scheme to vaccine procurement and the backing of our military personnel – has shown that we are at our strongest when we work together.”