Jeremy Corbyn has said he is not ruling out allowing a second Scottish independence referendum to be held if he becomes prime minister.
The Labour leader said he would “decide at the time” what to do if Nicola Sturgeon asked for his consent.
But he said his party does not want a referendum, and would be “very clear on why we don’t think it’s a good idea”.
Labour gave a “cast iron guarantee” before the last Holyrood election that it would oppose a referendum.
The Scottish Conservatives claimed Mr Corbyn’s comments showed that Labour is “utterly weak when it comes to Scotland’s place in the UK”.
In an interview with BBC Scotland ahead of the party’s conference, Mr Corbyn was asked what he would do if Ms Sturgeon, the Scottish first minister, asked for the power to hold another vote on independence.
Westminster’s consent would be need if any referendum was to be lawfully held.
Mr Corbyn replied: “We would obviously decide at the time”, before pointing to the £13bn funding gap in Scotland’s public finances.
He said a Labour government would invest money in Scotland through a £20bn transformation fund and a £3bn increase in revenue spending.
He predicted: “Things will be very different in Scotland with an ally in Westminster like a Labour government.”
‘Not ruling out’
When asked whether he was ruling out giving Ms Sturgeon consent for a referendum to be held, Mr Corbyn responded: “I’m not ruling out – I’m just pointing out the reality.
“We don’t want another referendum, we don’t think another referendum is a good idea, and we’ll be very clear on why we don’t think it’s a good idea.
“We think what’s more important is dealing with child poverty, housing problems and lack of investment in Scotland – 200,000 more children going into poverty has to be dealt with. A referendum will not solve that.”
In May of last year, then-Scottish Labour leader Kezia Dugdale said the party’s Holyrood election manifesto gave a “cast-iron guarantee” that it would oppose a second referendum.
She added: “The Labour Party, built on solidarity and co-operation, could never support taking our country down a divisive path like that again – our country is divided enough.
‘Wouldn’t block it’
It came two months after Mr Corbyn said he would be “absolutely fine” with another independence referendum, and that Labour “wouldn’t block it” if the Scottish Parliament voted in favour of one being held – which it has since done.
His comments were heavily criticised at the time by senior Scottish Labour figures including MSP Jackie Baillie and MP Ian Murray.
But Ms Sturgeon tweeted that it was “always a pleasure to have Jeremy Corbyn campaigning in Scotland”.
Responding to the Labour leader’s latest remarks, Scottish Conservative MSP Adam Tomkins said: “Every time Jeremy Corbyn talks about Scotland he gives yet another concession to the SNP.
“Jeremy Corbyn does not care about Scotland and has no interest in standing up to the nationalists, as this latest gaffe proves.”
BBC Scotland has launched a new podcast exploring the big political issues of the week at Holyrood and Westminster. The first episode of Podlitical is available now – with analysis of the Jeremy Corbyn interview. You can download it and subscribe wherever you get your podcasts.
What else did Mr Corbyn say in the BBC Scotland interview?
The Labour leader repeated his party’s position that it would vote down any “bad deal” on Brexit, and “certainly vote down a no deal”.
But he said a failure by the government to get its final Brexit plan approved by parliament should trigger a general election rather than another referendum on EU membership.
He said Labour would “negotiate immediately with Brussels on a trade and a customs arrangement with the European Union so that we have that close relationship” if it won the election.
Mr Corbyn added: “We’ve made it very clear we understand and respect the results of the referendum, but we also respect the fact that people need to keep jobs, we need to keep trade, we need to keep rights and we need to be part of the European system of human rights.”
He also stressed that the 2015 Brexit referendum had “made the decision” that the country would leave the EU, and that “we are not proposing another referendum”.
Mr Corbyn said: “I understand many people are (proposing one) but there are also many versions of what that referendum would be, which could actually be more complicated.”
The Labour conference will open in Liverpool on Sunday, and will run until Wednesday of next week.