Scottish Labour’s former leader Kezia Dugdale has said she once voted for the SNP because she was “so mad about Brexit”.
Ms Dugdale said she voted for the pro-independence party at the last European election before the UK left the EU.
However, Ms Dugdale, who is now director of the John Smith Centre at the University of Glasgow, said she has backed Labour in the other elections since then.
The former MSP led Scottish Labour between 2015 and 2017.
She spoke to BBC Radio 4 in recent weeks for an upcoming documentary on the general election battle in Scotland.
Ms Dugdale said: “I voted SNP once in my life and that was in the European Union elections immediately after Brexit, where I was so mad about Brexit, I wanted to register to register a vote for them. And for that reason alone.
“I felt I could vote for the SNP in that European Union election, because that in no way could be construed as a vote for independence.
“I felt that that was a safe thing to do. I voted Labour in every election since then, from the council to the Scottish Parliament, to the general election, I have used a vote for Labour.”
The former Scottish Labour leader, who is no longer a party member, is married to SNP Education Secretary Jenny Gilruth.
In August last year, Ms Dugdale said her stance on independence had “moved” as she could no longer argue as strongly for the union as she did in 2014, but was not necessarily ready to vote Yes in a referendum.
The BBC documentary also spoke to current Scottish Labour leader Anas Sarwar, who said he believes 28 Scottish seats are “in play” at the general election.
Mr Sarwar said: “People talk a lot about tipping points in the polls. I think the tipping point in Scotland is around 35% – if we get around 35% in the polls then we are in competition to beat the SNP.
“If I said that to anybody two-and-a-bit years ago, they would have thought I was deluded. But I have always believed that’s what we can do.”
First Minister and SNP leader Humza Yousaf said he looked forward to a “battle of ideas” at the general election.
He told the BBC: “I don’t fear a general election at all. I see it’s a huge opportunity.
“There’s no getting away from the fact that 2023 was a difficult year. I’m not going to treat you or your listeners as fools.”
He continued: “But the general election presents an opportunity because, ultimately, a general election will be and should be a battle of ideas.
“And I think the SNP is strongest when it’s talking about policy.”
Scottish Conservative chairman Craig Hoy said: “Pro-union voters will be dismayed that a former Labour leader could vote SNP and betray the union so easily.
“This is even more evidence that you can’t get a cigarette paper between the SNP and Labour as on a wide range of key issues – such as gender recognition reform and oil and gas – you can’t tell the two parties apart.
“The Scottish Conservatives are the only party that will stand up to the SNP and their divisive independence obsession.”
A spokesperson for Scottish Labour said: “There is an overwhelming majority in Scotland and across the UK for change.
“That means Scotland can lead the way in getting rid of the Tories and maximising Scotland’s influence in the UK.
“So, our message to all voters is the same – we don’t care how you voted in the past.
“We are the only party in this country trying to persuade anyone and to unify it around change.”