ShareSaveAdd as preferred on GoogleAngus CochraneSenior political journalist, BBC ScotlandGetty ImagesRussel Findlay, left, clashed with John Swinney, right, during the debate Scotland could have a second independence referendum as soon as 2028, First Minister John Swinney has said.
The SNP leader, who was facing other party leaders in a BBC Scotland Debate Night special in Paisley Town Hall, said it was "perfectly conceivable" that a vote on the constitution could be held within two years.
Green co-leader Ross Greer said Scotland's future should be "in Scotland's hands".
But Labour leader Anas Sarwar said next month's election was "not about independence", while Conservative chief Russell Findlay said the break-up of the UK would be an "unmitigated disaster".
Reform UK's Scottish leader, Malcolm Offord, said another referendum would be "divisive" - but did not rule out a future vote if support for a Yes vote reaches 60%.
Alex Cole-Hamilton, Scottish Liberal Democrat leader, said he had not given a second referendum "a moment's thought" because he was focused on other issues.
The party chiefs - who were asked questions by a live studio audience - also clashed over immigration, the NHS and energy during the debate.
A second independence referendum would need to be signed off by the UK government.
However, Prime Minister Sir Keir Starmer has said he cannot imagine another vote taking place during his time in 10 Downing Street.
Earlier on Sunday, Health Secretary Wes Streeting told LBC: "We're not having one" and added that "this country has had enough of chaos".
At the BBC debate, Swinney told the audience the people of Scotland were "entitled" to decide their own constitutional future.
However, he said the country was stuck in a "constitutional logjam" that could be broken by an SNP majority - which the party achieved ahead of the 2014 referendum.
The first minister urged voters to deliver an "emphatic mandate of an SNP majority so the future of our country can be taken into our own hands".
Asked when the vote could be held, he said it was "perfectly conceivable to have a second referendum by 2028".
Greer said a majority of pro-independence MSPs - from the Greens or SNP - in the next parliament would represent a mandate for a referendum.
He told the audience it was "profoundly anti-democratic" for Westminster to deny Scotland a second vote, and said independence could help the country solve major issues it faces with the NHS and economy.
Sarwar said the Scottish government should be focused on fixing the NHS, providing good jobs, building more homes and bringing down cost of living.
He added: "This election is not about independence, it's about having a government that works for the people of this country."
Findlay warned that a referendum could be given the green light by a "weak" prime minister, insisting his party would "stand up for Scotland's proud place in the union".
He urged Swinney to "get on with the day job", adding: "By every measure you've been distracted and Scotland has got worse."
Offord said: "People want Holyrood to get on with the day job and improve people's lives."
However, he accepted that the situation could change if support for independence increased.
Cole-Hamilton said the government should focus should be on other issues – citing the NHS, education and cost of living.
Control over immigration and borders is reserved to the UK government, but it has emerged as a major issue during the Holyrood election campaign.
Offord said he wanted "cohesion" in Scotland's communities - but claimed some people coming to the country were "jumping the queue" to the detriment of local people.
Findlay said: "People in Glasgow and other communities are seeing a system at breaking point with too much pressure on local services."
Glasgow houses more asylum seekers - about 3,800 - than any city outside of London.
Glasgow City Council leader Susan Aitken told BBC Scotland News last year that the city had essentially "run out of temporary accommodation".
Greer called Offord a "chancer" and called for more immigration to Scotland.
"The problem is we do not have enough immigration to meet the needs of the country," he said.
The Green co-leader said immigrants are needed for the NHS, social care and rural communities.
Cole-Hamilton accused Offord of "trying to win an election based on dividing the people of Scotland".
He said that while there was a problem with small boats crossings, immigration was needed to plug a "skills crisis".
Sarwar accused Offord of "questioning my loyalty to my country" and accused the Reform UK leader of attacking people from migrant backgrounds.
He said while skilled workers were needed for the economy, there was "unfairness" in the immigration system due to "illegal migration".
Swinney said some of the rhetoric on immigration had been "inflammatory" and backed calls for the UK government to allow asylum seekers to work.
There is a dispute ahead of every election in Scotland about whether it might lead to an independence referendum.
The UK Supreme Court ruled in 2022 that the constitution, including the union between Scotland and England, is a matter for Westminster rather than Holyrood.
Former First Minister Nicola Sturgeon had brought the case to query whether MSPs could legislate for an independence referendum.
Judges unanimously concluded that they could not do so without a transfer of powers from Westminster - known as a "section 30 order" - as happened ahead of the previous vote in 2014.
The question is whether the SNP can persuade UK ministers to grant such an order again.
The party had previously argued that a pro-independence majority at Holyrood should be enough to do this.
But the SNP and Greens had just such a majority last term, at the time of the Supreme Court ruling, and John Swinney now says an outright SNP majority would provide a mandate - noting that this is what happened for the 2014 vote.
