Mike Russell told MSPs at Holyrood that if the UK quits the European Union without a deal there would be “an even greater urgency to give Scotland a choice of a different future”.
With hardliners such as Boris Johnson and Michael Gove now vying to become the next prime minister, the Scottish Constitutional Relations Secretary warned they were “heading with pleasure to the cliff-edge” of a no-deal Brexit.
After the Referendums (Scotland) Bill was published, he said: “It is the intention of the government to offer the people of Scotland a choice on independence later in the term of this Parliament.
“Of course, should circumstances change, we would have the option of seeking Parliament’s agreement to proceed at an accelerated timetable.”
With several prominent pro-Brexit Conservatives hoping to succeed Theresa May, Mr Russell said: “A Boris Johnson premiership is no longer a bad joke, it is a frightening possibility.
“Substitute Raab or Leadsom or Gove or Hancock or any of the others for Johnson and the situation is no better.
“Most are heading with pleasure to the cliff-edge. But Scotland must not be forced against our will to go with them.”
Three Tory leadership contenders – UK Justice Secretary Sajid Javid, Health Secretary Matt Hancock and International Development Secretary Rory Stewart – reacted to the unveiling of the bill yesterday by ruling out another referendum.
Mr Javid said on Twitter: “If I become PM, I won’t allow a second Scottish independence referendum. People stated views clearly in 2014, so there should be no second vote. Nicola Sturgeon should spend more time improving public services in Scotland, and less time grandstanding.”
Mr Stewart said: “In everything we do and everything we say in this leadership race we should remember that the key is to unify the country and not divide the United Kingdom.”
Mr Hancock said: “The people have spoken. No way, Nicola.”
Ms Sturgeon responded by saying Westminster’s refusal to hand Holyrood the power to stage a second vote on leaving the UK is “unsustainable”.
She tweeted: “Memo to Tory leadership candidates: A majority of Scots – independence supporters and opponents alike – will not accept being told by a Tory PM that we are not ‘allowed’ to choose our own future.”
Ms Sturgeon had earlier said that it would be a “democratic outrage” if Westminster were to block Scotland from holding a second referendum.
The First Minister said: “Throughout the Brexit process, Scotland has been treated with contempt by Westminster, and our efforts to find compromise and protect the interests of the people of Scotland, who voted overwhelmingly to remain in the EU, have been ignored.”
The Bill – which has 42 sections – provides a “legal framework for the holding of referendums on matters that are within the competence of the Scottish Parliament”, accompanying papers said.
These made clear: “The main policy objective of the Bill is to ensure that future referendums on matters that are within the competence of the Scottish Parliament maintain the high standards achieved by the referendum on Scottish independence in 2014.”
They also stipulated that when determining what questions are to be asked of voters, Scottish ministers “must consult the Electoral Commission”.
While having the UK government legislate for future referendums would be an “alternative approach”, Scottish Government papers stated: “This would not be an effective or acceptable option. The Scottish Parliament should set the rules for referendums within its legislative competence, as this is the only legislative approach that respects the rights and role of the Parliament.”
Scottish Conservative constitution spokesman Adam Tomkins said: “In reality, this is Nicola Sturgeon laying the ground for a ‘wildcat’ second referendum on independence.” He added: “Under this bill, SNP ministers would have the power to set any referendum question, at any time, on any matter of their choosing. It’s a power grab on an industrial scale.”
Scottish Labour leader Richard Leonard said the Scottish Government was only “seeking to advance the cause of the break-up of the United Kingdom” by publishing the bill.
And Scottish Liberal Democrat leader Willie Rennie said that SNP ministers had “learnt nothing from the chaos of Brexit”.
“Independence will mount chaos on top of the Brexit chaos,” he said.