AN increasingly acrimonious split in the independence movement over the date of a second referendum has forced an SNP MP to call for calm after being subject to online abuse.

Pete Wishart said he had been called a Unionist “poster boy” and an “Etonian boot licker” by fellow Nationalists after urging pragmatism, rather than rushing into a new vote.

He said he had been taken aback by the “vehemence" of people he presumed were political colleagues, and admitted the Yes campaign had a problem with online abuse.

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The Perthshire MP, who is chair of the Commons Scottish Affairs Committee, wrote about the attacks on his blog in an article entitled “We must conduct our debate with respect”.

He said: “It would be easy to dismissed this as ‘just Twitter’ but I know that environment reasonably well and I have to conclude we might have an issue and difficulty in our movement.”

He added: “Shouting people down, name calling and misrepresenting people’s views will not help anybody. If this happens people with legitimate views will be silenced and discouraged in coming forward with their own views.

“No one in our movement has all the answers and at this juncture in the fight for our nation’s independence we need as much input and ideas as possible.

“I will certainly not be deterred from forcefully speaking my mind and I will not be silenced.

“I will continue to put forward what I think is right for my country and right for the case in securing our nation’s independence.”

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After calling a second referendum a year ago, First Minister Nicola Sturgeon “reset” her plan in the wake of the SNP losing a third of its MPs in the June election.

She is due to update MSPs on "the precise timescale for offering people a choice over the country’s future” in the autumn.

Some Yes campaigners argue she is duty bound to use the “triple lock” mandate she sought and - by her own benchmark - achieved in the general election to push for a new vote.

However senior party figures, including former Justice Secretary Kenneth MacAskill and Mr Wishart, say it would be folly to have a referendum without clear public support for Yes.

A new poll on Sunday found most Scots opposed both a referendum and independence.

Mr Wishart, the SNP’s longest-serving MP, last week wrote an article in iScot magazine saying it would be a “national tragedy” to hold a referendum before the country was supportive, and defeat would set the independence cause back “decades”.

He said his general election experience was that the push for a fresh plebiscite had alienated many voters, and resulted in the Tories slashing his majority from about 10,000 to just 21.

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Mr Wishart said his “crime” or urging pragmatism had unleashed “the most extraordinary response on Twitter” and led him to question how the Yes movement debated the issue.

He said he was accused of being “defeatist”, of “depressing” the Yes movement, and of being too settled in his Westminster lifestyle.

He revealed similar abuse had been a factor in not seeking the SNP deputy leadership, and appealed for unity in the Yes camp.

“I was concerned that the debate might descend into what I have just experienced and I didn’t want our contest dominated with all of this,” he said.

Labour MSP Rhoda Grant said: "This is an extraordinary and welcome intervention by Pete Wishart. For years, politicians from across the political spectrum have been warning about the scale of abuse they face, particularly on social media.

"Personal abuse and insults should have no place in political debate - and it is essential politicians themselves lead the way.

"It is essential elected members from all parties, as well as the wider public, work together to tackle abuse on social media."

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A Tory spokesman said: “Pete Wishart is stating the obvious. As one of the Yes campaign’s most erratic Twitter users, perhaps he should look in the mirror when looking for blame.”

Labour and the Tories have also had problems with online abuse.

The SNP is due to publish its new prospectus for independence imminently, after an 18-month study by its Growth Commission.

However the Sunday Herald reported this could back a centre-right free market New Zealand model, rather than the centre-left Scandinavian model backed by many in the Yes movement.