Former SNP depute leader Jim Sillars has said another referendum on independence should not be held until 60% support has been secured in opinion polls.

Mr Sillars, who remains a member of the SNP, hosted a fringe event at the inaugural Alba Party conference, where he discussed the relationship between the two parties and the future of the independence campaign.

First Minister Nicola Sturgeon announced this week that civil servants were working on a “prospectus” for an independent Scotland, with the co-operation agreement struck with the Scottish Greens pledging another referendum by 2023.

Speaking at the event, Mr Sillars said another vote held too soon would sink the independence cause, and he encouraged people within the movement to move away from what he called the “referendum fairytale”.

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“You don’t want a referendum unless you’ve built up the amount of support which makes sure you’re going to win it,” he said.

“If I was Boris Johnson, I would offer us a referendum in March, because we wouldn’t win it.”

He added: “We’ve got to get to 60% of solid, rock-hard support.”

HeraldScotland:

Jim Sillars, beside Nicola Sturgeon, during the last Indyref

That 60% figure, Mr Sillars said, would give the independence campaign a cushion in any forthcoming vote, meaning they would still hold a majority if some voters switched their vote at the last minute.

In recent weeks, Scottish Secretary Alister Jack said another referendum could be on the cards if 60% support is achieved in opinion polls.

Mr Sillars said “we should back that”, adding that it would give the movement “something to aim for” if it was made UK Government policy.

The former depute leader went on to urge Alba and the SNP to work together, although he conceded this was unlikely under the current leadership of the ruling party.

“This movement of ours, with the construction of Alba and the existence of the SNP… has been split,” he said.

“And if we continue to be split, it will be a serious handicap when we try to win people over for independence.

“To restore unity in the movement is not going to be easy.”

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Mr Sillars went on to say it would be important for rank and file members of both parties to continue to have a dialogue.

He continued: “What I hope for is after the dust has settled, as long as people can talk to each other, there will be some federal relationship between Alba and the SNP.

“It would be a united movement, but Alba would be very distinctive, it won’t be a subordinate party… and we try to restore the unity that way.”