Former prime minister Gordon Brown claimed Scotland could vote for independence if major economic and social problems in the UK are not fixed.
The ex-Labour leader said a second referendum could take place in his lifetime during an interview on Sky News.
But Mr Brown, who was MP for Kirkcaldy and Cowdenbeath, believes Scotland “deserves better” than an endless row over independence.
It comes after Nicola Sturgeon announced on Tuesday she wants to hold a rerun of the 2014 referendum in October next year.
The first minister warned the SNP would fight the next Westminster election solely on a promise to deliver independence if a ballot on leaving the UK is not granted.
When asked if a referendum could take place eventually, Mr Brown said: “I wouldn’t rule out that.
‘Endless debate’
“But I would say Scotland deserves better than what’s happening at the moment. We’re in an endless debate about constitutional details that is leading us nowhere.
“I would like to see – and I would like to put forward – a far more ambitious plan for the future of Scotland.”
He added: “If the issue is posed as change through independence versus no change, and the only alternative is independence, then independence will be something that people would be prepared to consider.
“But if it’s one kind of change for Scotland staying within Britain, but in a better situation both in terms of its economic, social and political future as against independence, then the change that is within Britain will win.”
Scottish Labour leader Anas Sarwar warned against Ms Sturgeon’s referendum plans this week and insisted the SNP should instead focus on Scotland’s Covid recovery.
Mr Brown is currently working on a commission for Labour exploring the future of the union.
His intervention during the 2014 independence referendum was credited as giving a major boost to the pro-union campaign.
Last year Mr Brown claimed Scotland and England were “moving closer together”.
The former Fife MP also gave his backing to current Labour leader Sir Keir Starmer.
He said: “We’ve got to find a way of bringing this country together, and I think Keir Starmer is better placed to do that than Boris Johnson.”
COURIER OPINION: For IndyRef2 to happen there are more hurdles to overcome than the Grand National