The ruling Scottish National Party has pledged to hold an independence referendum by the end of 2023, a step that could fracture the United Kingdom by ripping apart the 314-year union between England and Scotland.
If there was another referendum and the Scots voted out, it would mark the biggest shock to the UK since Irish independence a century ago.
Scotland voted against independence by 55 per cent to 45 per cent in 2014 but Nicola Sturgeon's SNP wants another referendum if it wins the Scottish parliament election on May 6.
UK Prime Minister Boris Johnson has repeatedly dismissed SNP calls for a referendum.
"We believe the people of Scotland should have the opportunity in a referendum when the COVID crisis is over to decide whether Scotland should be an independent country," the SNP said in its manifesto published on Thursday.
"The SNP intention is for the referendum to be within the first half of the five year term," the SNP said, adding that the date of the referendum would be "determined by our democratically elected parliament".
Although Johnson has the power to refuse another independence vote he would likely face a constitutional showdown with Scotland.
The SNP said that if it won a majority in May then the Scottish parliament would pass a referendum bill, which proposes that the question on the ballot be: "Should Scotland be an independent country?"
"There can be no moral or democratic justification for Boris Johnson or any Westminster government to obstruct the right of the people of Scotland to decide their own future," the SNP said.
The SNP currently has 61 of the 129 seats in the Scottish parliament but by working with the Greens' five lawmakers, it has effective control of the devolved parliament.
Australian Associated Press