Jeremy Corbyn has ruled out a second Scottish independence referendum in the first two years of a Labour Government, saying one would "certainly not" take place.
"Certainly not in the first two years of the government, we certainly would not be countenancing an independence referendum," he said, when asked if the 2021 Holyrood election result could play a part in such a decision.
The Conservatives fear labour could do a deal with the SNP over an independence referendum in a bid to win the keys to Downing Street, and promising them another vote would be a sure way of securing a deal.
On Wednesday, Mr Corbyn kicked off a two-day tour of Scotland in Glasgow, aiming to help his party retake some of the seats it lost to the SNP landslide in the 2015 general election.
However, Scottish National Party (SNP) leader Nicola Sturgeon appeared to make fun at Labour's changing stance.
The SNP leader tweeted: "Yesterday it was 'not in the first term'. Today, it's 'not in the first two years'. By the end of the week, at this rate, Corbyn will be demanding #indyref2020."
Ms Sturgeon has already set out plans to hold a second independence referendum in the later part of 2020, and will write to the prime minister - whoever that may be - shortly after the election to demand the power to do so.
Asked about her disagreement with the Labour leader about her timetable for another independence vote, Ms Sturgeon added: "I think Jeremy Corbyn should go with his own instincts on this, he's getting himself into a mess because in his heart of hearts he knows that the only democratically defensible position is to accept that it's not for Westminster to decide the future of Scotland.
"I think he's trying to spare the blushes of Scottish Labour while he's here because their position is nonsensical and he's getting himself into a mess."
But with the SNP also in favour of holding a second Brexit referendum, Scottish Conservative leader Jackson Carlaw pressed Ms Sturgeon on her "big double referendum promise".
During First Minister's Questions, he called on Ms Sturgeon to "clarify" details of the timings for such votes.
He said: "As she keeps telling us, she would ask Jeremy Corbyn for a referendum on independence and demand it's held next year.
"And we know too that she would support Mr Corbyn's plan for a second Brexit referendum, also to be held next year.
"Now First Minister, clarify for me a simple question on timetabling. When is all this supposed to happen? Both referendums on the one day or different days?
"Which vote would come first - indyref, euroref - which?"
Ms Sturgeon replied: "My priority - and I can't believe Jackson Carlaw hasn't actually cottoned on to this yet, he should maybe listen a bit more - my priority is to give the people of Scotland the opportunity to choose independence next year and I look forward to delivering on that."
Ms Sturgeon defended prioritising another vote on independence over EU membership during a campaign visit to Hawick with SNP candidate Calum Kerr.
"I've supported a second Brexit referendum, but it's not something that is within my power to deliver," Ms Sturgeon said.
"The SNP, as long we are in Westminster, will support anything that allows the UK to reconsider the issue of Brexit but that's for the House of Commons to decide.
"It remains far from certain that that is going to happen.
"Fundamentally, the solution - not just to Brexit, but to a situation where we are having our future imposed on us by Westminster - is to have the ability to take our future into our own hands and that comes through an independence referendum."