A SENIOR SNP MP has criticised one of Nicola Sturgeon’s closest advisers after he urged a slow build-up to the “softest possible” form of independence.

Joanna Cherry QC, the SNP’s justice spokesperson at Westminster, took to Twitter to publicly disagree with Andrew Wilson, the author of the party’s Growth Commission.

She said independence was needed as soon as possible to protect Scotland from Brexit, and promoted the call for a second referendum.

The intervention underlined splits in the Yes movement over the timing and strategy of another referendum as the First Minister delays her long-awaited update on the issue.

READ MORE: Key Sturgeon adviser urges 'softest possible form of Scottish independence'

Mr Wilson, a former MSP turned corporate lobbyist, said on Thursday that Ms Sturgeon should play a long and minimalist game on independence in order to woo voters.

He wrote in The National: “In the parlance of Brexit, we offer the softest of possible changes to the current arrangements, not the hardest. We recognise the level of integration and all the ties that have bound us for centuries. We create a platform that can unify a majority for progress that stands a chance of winning and winning big.”

He said more time was needed to recast the 2014 case for independence, likened leaving the UK to a “process rather than an event” and said Scotland was on a “journey without end”.

He also mocked those Yes supporters who want independence to be abrupt and radical.

“Some (a very small number) would rather move immediately and overnight to a Marxist revolutionary state. That is their right, but they won’t win the chance to try,” he said.

The comments drew a sharp response from Ms Cherry on Twitter.

She said: “You don’t have to be a ‘Marxist revolutionary’ to disagree with this softly softly strategy. Brexit is a catastrophe about to hit Scotland & the only way to protect our society & economy is #independence #indyref2.”

In a second tweet, she added: “As an MP on the #Brexit Select committee I’ve watched this disaster proceed in the face of all the evidence.

“I’m also aware that many of #EU27 are very sympathetic to #independence for Scotland & once UK is 3rd state that can translate to action #indyref2.”

READ MORE: SNP MP warns against 'bouncing' country into Indyref2

Jonathon Shafi, co-founder of the pro-independence far-left Rise alliance, also criticised the reference to a Marxist revolutionary state as “disingenuous from Andrew Wilson”.

He said: “For the sake of the debates and discussions @AndrewWilson should stop referring to opposition to the Growth Commission or the "softly softly" approach as a Marxist fringe. It does not help to the quality of the discourse and the movement deserves better.”

Mr Shafi added: “I think this approach [to independence] simply begs the question: then what is the point?”

Chris McEleny, the leader of the SNP opposition on Inverclyde Council, and a candidate for SNP deputy leader last year, said: “Independence isn’t about a soft or hard independence. “It’s about the people of Scotland having their own choice. A choice between staying part of a union that gives us no choice on the EU, the poll tax, illegal wars, Trident, the rape clause and austerity, or the choice to live in a country where the people make all the choices that affect the way we live. Whether you think that’s ‘hard’ or ‘soft’ is irrelevant.”

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The anti-independence group Scotland in Union said there was no such thing as soft independence, and voters would not be fooled by the new sales pitch.

Mr Wilson last year produced a new economic blueprint for independence advocating a decade of public spending restraint and keeping the pound.