FORMER SNP deputy leader Jim Sillars has warned his party it must shift to the left to retain power.

The veteran independence campaigner believes the SNP could lose power because of support for Labour leader Jeremy Corbyn's policies, particularly in Scotland's Central Belt.

Sillars issued the stark warning to his party ahead of the start of the SNP conference in Glasgow today.

In an interview with the Sunday Herald to mark his 80th birthday he said working-class areas in Scotland's Central Belt would be a key battleground between Labour and the SNP. And if left-winger Richard Leonard's was Scottish Labour leader SNP MSPs there would be vulnerable.

When asked if the SNP could lose its majority at Holyrood, Sillars said: "I believe they could".

Sillars believes the SNP leadership has failed to grasp the threat Corbyn poses to its grip on office.

He said that "what Corbyn's been punting is a distinctive socialist answer to the austerity created by modern capitalism. That will be a massive factor in Labour's favour across the Central Belt.

"That socialist approach has attraction and Labour has regained belief in Scotland. The SNP now faces a formidable foe at Westminster. Unless the SNP comes up with more left-wing policies it will find itself in difficulty."

Sillars said Corbyn's "distinctive socialist answer" was attracting independence supporters in Central Scotland.

The SNP lost six Westminster seats to Labour in the election in June. But Sillars warned that the party faced losses to Labour on a much greater scale at the 2021 Holyrood election

Sillars served as a Labour MP for South Ayrshire and later as the SNP MP for Glasgow Govan. But he said that Corbyn's opposition to independence meant he could not leave the SNP to rejoin Labour.

However, he warned that Corbyn's plans for renationalisation and wealth redistribution were popular with working-class Yes voters.

He said members of his own family who were "serious" independence supporters had voted for Corbyn on June 8.

"I read the Labour Party manifesto and I found very little to disagree with," he said.

"I don't know whether people are aware of the Corbyn threat. They don't understand what's at the heart of Corbyn's programme.

"It's not a Marxist analysis of capitalism. But everybody knows that the idea that we live and die by the market is a blatant lie.

Sillars suggested that Richard Leonard could be swept to power on a Corbynite platform in 2021 even although Scottish Labour is now the third party at Holyrood.

However, he said that if Anas Sarwar was elected "all that I've said can be cancelled out”.