The Scottish National Party has revealed a "roadmap to a referendum" on Scottish independence, setting out how they intend to take forward their plans for a second vote.
Mike Russell, the Scottish government's constitution secretary, will present the 11-point document to the party's policy forum on Sunday.
It says a "legal referendum" will be held after the pandemic if there is a pro-independence majority following May's election.
The roadmap states any attempt by the UK government to challenge the legality of the referendum in the courts will be "vigorously opposed".
A Section 30 order – part of the Scotland Act 1998 which allows Holyrood to pass laws normally reserved to Westminster – was granted by the UK government ahead of the 2014 independence referendum.
Mr Russell says the UK government could either agree that Holyrood already has the power to hold a second referendum or agree to a Section 30 order – something he said would put the question of legality "beyond any doubt".
Boris Johnson has repeatedly stated his opposition to a second independence referendum.
As the roadmap document was published on Saturday, Mr Russell said: "I firmly believe that Scotland's referendum must be beyond legal challenge to ensure legitimacy and acceptance at home and abroad.
"This is the surest way by far to becoming an independent country.
"The referendum should be held after the pandemic, at a time to be decided by the democratically elected Scottish Parliament. The SNP believes that should be in the early part of the new term."
He continued: "Today I am setting out how I believe that right can be secured, and I welcome the discussion that will take place around this idea and others.
"But what is absolutely not for discussion is the fact that if Scotland votes for a legal referendum on May 6 this year, that is what it will get.
"The SNP Scottish government will deliver such a referendum if re-elected and the proposals I am putting forward make that very clear."
Around 1,000 party members are expected to take part in the SNP's national assembly tomorrow, a policy forum chaired by deputy leader Keith Brown.
Opposition parties accused the SNP of putting the push for independence ahead of the coronavirus pandemic.
Scottish Labour interim leader Jackie Baillie said: "Scotland is deep in turmoil with thousands facing a cost of living crisis and thousands more people being lost to the virus.
"It is inexcusable that at this time of acute crisis the SNP seeks to put its plan for independence above everything else.
"The people of Scotland are being badly let down by an incompetent UK government and a Scottish Government that seeks to exploit the current crisis for its own ends.
"To turn your back on those most in need by banging the drum for another independence referendum is an act of political hubris and is truly revealing of the Scottish government's true priorities."
Scottish Conservative leader Douglas Ross tweeted: "When 100 per cent of our focus should be on recovering from the pandemic, the SNP are charging ahead with plans for another referendum.
"We won't let them get their way."
Responding to the SNP's document, the UK government said the issue of Scottish independence had been settled "decisively" in 2014.
A spokeswoman said: "People in Scotland want to see politicians across the UK working in partnership to focus on defeating coronavirus.
"That remains the top priority of the UK government, which has supported jobs and businesses across all four nations throughout the pandemic.
"The government is supporting the devolved administrations in their vaccination programmes, with the British Armed Forces helping to establish 80 new Covid-19 vaccine centres in Scotland.
"The question of Scottish independence was settled decisively in 2014, when Scotland voted to remain part of the UK.
"Now more than ever, we should be pulling together to strengthen our United Kingdom, instead of trying to separate it."
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