A fisherman who has campaigned with Scottish Conservative leader Ruth Davidson has been reported to police over a series of abusive messages to First Minister Nicola Sturgeon.

Peterhead skipper John William Buchan is facing an investigation for a string of messages on his Twitter page, which call for the SNP leader to “taken down” and Holyrood to be “blown up”.

In another tweet, there is a photograph of former first minister and Gordon candidate Alex Salmond with the words “would love to fill that smug face in” underneath.

Racist messages have also been posted on his social media pages, alongside a story about a Calais migrant being run over and killed.

Mr Buchan, who is skipper of the Atlantic Challenge – the largest vessel in the Scottish deep water fleet – last night declined to comment.

He was pictured side-by-side with Ms Davidson on her visit to Peterhead earlier this week as she campaigned for the general election.

A SNP spokeswoman last night confirmed the abuse had been reported to the police, and said the revelations were “deeply embarrassing” for Ms Davidson.

She said: “The Tories in Scotland are moving further and further to the right, fast becoming Scotland’s UKIP. That’s why we need a strong SNP voices to stand up to them at Westminster.

“But it’s disturbing to know these extremist, vile, right-wing views exist among Ruth Davidson’s closest political allies.

“It’s deeply embarrassing for the Tory leader.

“Ruth Davidson and David Duguid should be unequivocal in their condemnation of such violent language – and consider whether an angry extremist is best trotted out to defend Tory lies over fishing.”

A Scottish Conservative spokesman declined to comment.

Mr Buchan, a former director of both the Scottish White Fish Producers’ Association and the Scottish Pelagic Fishermen’s Association, refused to comment when contacted by the Press and Journal last night.

He said: “I’ve got nothing to say to you.”

The complainant, who wished to remain anonymous, said: “I was shocked when I saw threats had been made on social media about the first minister and other politicians.

“It is our democratic right to debate and have opposing views but to make such violent threats is abhorrent, particularly when the last year has shown that threats to politicians are real and can be life-changing.

“The person behind these tweets should be questioned over their actions.”