Jeremy Corbyn has said a new Scottish independence referendum is “not necessary or desirable”.
The Labour leader spoke out after Nicola Sturgeon claimed he would agree to hold another vote on Scotland leaving the UK if he becomes prime minister.
Ms Sturgeon is expected to demand the power to stage a second Scottish independence referendum just days after December’s General Election.
In response, Mr Corbyn said: “Labour does not support independence for Scotland and we do not think another independence referendum is either desirable or necessary.
“We are running the most radical, people-focused election campaign the UK has ever seen and if we win we will invest £70 billion in Scotland over the next decade.
“Our promise to the people of Scotland, and people across the UK, is that a Labour Government will end austerity, tackle the climate emergency and invest in our communities to truly transform society.”
Ms Sturgeon earlier said she wants Scots to “demonstrate the desire” for independence by voting for her party.
The SNP leader added opposition to another referendum is not sustainable.
I don't think Jeremy Corbyn is under any illusions about my position around independence and a referendumNicola Sturgeon
When asked at an election rally in Leith, Edinburgh, whether she believes Labour would grant a Section 30 Order to enable a vote on Scottish independence, Ms Sturgeon answered emphatically: “Yes.”
Explaining her confidence, she added: “I’m a believer in the power of democracy.
“If people in Scotland demonstrate the desire – as I believe they will in this election – for an independence referendum, then I don’t believe Westminster opposition to the principle or to the timetable to that will prove to be sustainable.”
Ms Sturgeon added: “Everybody knows there’s going to be an independence referendum.
“The opposition parties might not have got round to conceding that point in public but they know it and everybody knows it.”
While Ms Sturgeon has held talks with Mr Corbyn recently, she revealed they did not discuss the issue of independence.
She said: “I met with him last week – that was the most recent occasion – and that was about Brexit and the prospects, as they were then, of an election.
“I don’t think Jeremy Corbyn is under any illusions, though, about my position around independence and a referendum.”
Ms Sturgeon said she would send a letter “before Christmas” to whoever is in 10 Downing Street requesting powers under Section 30 of the Scotland Act 1998 to grant the Scottish Parliament powers to hold another independence referendum.
She also warned of a future where “you’ll have Nigel Farage and Donald Trump pulling Boris Johnson’s strings”, following the US president’s comments that Mr Johnson and the Brexit Party leader working together would be “unstoppable”.
Scottish Liberal Democrat leader Willie Rennie accused Labour of being willing to grant another referendum, while he said the Conservatives are “proposing a border down the middle of the Irish Sea”.
He said: “Scotland doesn’t need another independence referendum.
“Scottish Liberal Democrats are now the only ones who can be trusted to stand up for the union.”
Scottish Conservative acting leader Jackson Carlaw said: “Nicola Sturgeon and I can finally agree on one thing.
“There’s little doubt now that as prime minister, Jeremy Corbyn would cave in to the SNP on another referendum immediately.”