The UK Labour Party deputy leader Tom Watson has spoken out against a second Scottish independence referendum.
It follows comments by shadow chancellor John McDonnell that a future Labour government would not block another vote.
Mr Watson said another referendum “is not the answer” to Tory austerity and Brexit.
He added that he fully endorsed the position of Scottish Labour leader Richard Leonard.
His intervention comes after Mr McDonnell told an audience in Edinburgh last week that any decision about holding an independence vote would be up to the Scottish Parliament.
And it follows a warning by ex-Labour prime minister Gordon Brown, who said unionism “appears to be sleepwalking into oblivion”.
In a video released on Sunday, Mr Watson said: “We can see the mess caused by the prospect of the UK leaving the four decade-long union with Europe – imagine how much more disruptive it would be to break our three centuries-long Union of Scotland within the UK.”
He pointed out that the party’s Scottish leader Richard Leonard had already made it “absolutely clear” that there was no case for a second independence referendum.
Mr Watson added: “As we said in our 2017 manifesto, Labour opposes another referendum and the turbo-charged austerity in Scotland that leaving the UK would cause, with the inevitable threat to thousands of jobs and livelihoods.
“That is not because our society doesn’t need to change. It does, and badly.
“But another independence referendum isn’t the answer. More nationalism, more uncertainty, and more division isn’t the answer.”
SNP deputy leader Keith Brown said: “People across the UK overwhelmingly believe that independence should be a matter for the Scottish Parliament and the Scottish people – not Westminster.
“UK voters believe it should be up to people of Scotland to decide how they are governed – not a Tory party which has no mandate in Scotland, putting our economy at risk to suit their own political ends.”