Labour deputy leader Tom Watson has spoken out against a second Scottish independence referendum, after shadow chancellor John McDonnell said a future Labour government would not block another vote.

Mr Watson said another referendum "is not the answer" to Tory austerity and Brexit, and 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".

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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.

"Last year Richard Leonard our Scottish leader said: 'We want to be absolutely clear to the people of Scotland that there is no case for a second independence referendum'.

"'We just had a referendum in 2014. We think that settled the will of the people of Scotland'.

"I want to endorse the statement from our independently elected leader of the Labour party in Scotland."

Mr Watson goes on to say: "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.

"Almost a decade of austerity has left our public services on their knees and Brexit has damaged our economy and divided our communities. The future is uncertain.

"But another independence referendum isn't the answer.

"More nationalism, more uncertainty, and more division isn't the answer."

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The Scottish Labour party raised concerns about the national leadership's position after Mr McDonnell's comments in conversation with Iain Dale on Tuesday, when he said of another potential referendum: "We would not block something like that. We would let the Scottish people decide. That's democracy.

"There are other views within the party but that's our view."

He said during another appearance at the Fringe the following day: "My view is exactly in line with Richard Leonard, which is we concentrate on the real issues, the independence referendum is a complete diversion.

"But I've also said continuously, I'm not being set up by Nicola Sturgeon to blame the UK Government for blocking the will of the Scottish people - that's too trite a political manoeuvre that's been taken on at the moment.

"In the situation we're in at the moment, my view is that we will not be blocking a proposal."

A new poll suggests 41% of people in the UK believe a Westminster government should allow the Scottish Government to hold an independence referendum if the request is made in the next five years.

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Around a third (32%) of the 2,003 adults questioned by Opinium said the UK Government should prevent another referendum, with the remainder saying they did not know or choosing neither option.

SNP depute 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."