NICOLA Sturgeon has backed a suggestion that there could be an “exodus” of Labour members if the party were to agree to a Brexit deal which ended freedom of movement.

Former Scottish Labour chair Jamie Glackin tweeted that he would be part of a wave of departures under such circumstances.

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“If the Labour Party signs up to a deal ending free movement then watch the exodus. Starting with me,” he wrote.

The First Minister responded: “I suspect this will be the view of many members/supporters of Scottish Labour should such a deal be done.”

The development came amid talks between Labour leader Jeremy Corbyn and the Prime Minister in a bid to reach a compromise on her Brexit deal and resolve a Commons stalemate.

Theresa May has repeatedly underlined one of her red lines is to oppose single market membership which would entail freedom of movement as she wants to restrict immigration from the EU. Corbyn has also opposed freedom of movement, however under internal party pressure Labour has softened its position, with shadow Brexit Secretary Sir Keir Starmer saying the UK should “explore” allowing qualified free movement of workers from the EU after Brexit.

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In February, he called for alignment with the EU’s single market.

Last night one Labour insider said opposing freedom of movement could be the last straw for many members across the UK.

“Apart from some parts of the north of England, I would say Labour members do back freedom of movement. Most Labour MPs in the UK are in big cities – London, Liverpool, Manchester – where there is a recognition of the importance of freedom of movement,” said the insider.

“I think lots of members would leave if Labour backed a deal which didn’t include freedom of movement.

"For many it would be the final straw. The Labour party is an internationalist party which believes in solidarity with workers across the globe, and to oppose freedom of movement would go against the founding principles of the party.”

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Sturgeon’s warning follows remarks by SNP Westminster leader Ian Blackford, pictured below, that Labour will pay a price at the ballot box in Scotland if a deal with the Tories increases the risk of a hard Brexit. Blackford said if someone like Boris Johnson were to become PM, the risk of a hard Brexit would be “very real”.

He told BBC Sunday Politics Scotland: “There are no guarantees through this process, and the risk of having a hard Brexit, having Scotland being outwith not just the single market and the customs union, would be very real, and I would say to Labour don’t do this, be very careful with what you are doing or quite simply you will pay a price at the ballot box in Scotland.”

A Labour for the single market campaign was launched last year and backed by politicians such as the Edinburgh South MP Ian Murray, former Scottish Labour leader Kezia Dugdale and the former MEP Catherine Stihler.

Last year, a row broke out ahead of the Scottish Labour conference after its leadership moved to block a vote on single market membership. Pro-single market campaigners had hoped to use a Brexit debate to call for the UK to remain in the trading bloc. But the party’s ruling body said the “situation regarding Brexit has changed significantly” in recent weeks.

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At the time Stihler said there was “simply no left-wing argument for leaving the European single market” as it protected workers’ rights.

She added: “It will be disappointing if members who support single market membership don’t get the opportunity to put that to a vote, but the campaign to protect jobs and defend workers’ rights will continue.”

Glackin said at the time that a “healthy party” would encourage members to express their views, adding: The days of control freakery in the Labour machine have not actually gone at all.

"Indeed ... it does look like it has got significantly worse.”