THE SNP has mocked Ruth Davidson claiming she is facing a "mutiny" from right-wing Brexiteers at the Scottish Tory conference.

The comments follow revelations that three Scots Tory MPs signed a letter to Theresa May calling on the UK to make a clean break with the EU.

SNP MSP Ivan McKee said the move showed Davidson was losing her "grip over her party" ahead of its annual conference in Aberdeen this week.

Davidson had called for the UK to be able to operate and trade within the single market "to the maximum possible extent".

She said she could "certainly" oppose the UK government's policy on future EU relations if she felt it would be damaging.

However, McKee said the letter to May signed by Alister Jack, Stephen Kerr and Colin Clark showed her MPs were in "open rebellion" by backing the most extreme Brexit possible.

The letter was sent by the European Research Group of Tory backbenchers, which is headed by leading Brexiteer Jacob Rees-Mogg.

McKee said the Scottish Tory conference on Friday and Saturday this week was "guaranteed to be a Brexit barney".

He said: “Ruth Davidson is heading for her conference next week with a mutiny on her hands. Her MPs are now in open rebellion – aligning themselves with the most right-wing Brexiteers and piling pressure on the PM to crash the UK economy out of the single market and customs union.

“The damage that would mean in terms of Scottish jobs and living standards is completely indefensible, and she knows it. Next weekend is guaranteed to be a Brexit barney for the Tories in Aberdeen, and will only undermine her authority further.

“As Ruth Davidson continues to lose grip over her party, as the Tories continue to make a hash of Brexit and her Westminster colleagues continue to slash Scotland’s budget, the tide of public opinion will continue to turn against her. Now more than ever it’s clear that Brexit will be Ruth Davidson’s undoing.”

However, Davidson insisted the Scottish Tories had a "united message" ahead of the conference in the Granite city.

She said: “This week is an opportunity for us to show how all of us at Holyrood, Westminster and in council chambers intend to deliver for Scotland. What’s now clear is that we are the only party in Scotland that can stand up against the SNP and take them on.

“After its previous leader gave up and packed in, Scottish Labour has once again become a branch office. By contrast, our own Scottish representatives at Westminster and Holyrood will take top billing at conference this week – to show we have a clear plan to take Scotland forward. All of us will have a united message: that the Scottish Conservatives want to deliver for Scotland and set out a fresh, positive agenda for the country.”

A Scottish Tory spokeswoman added: “Ivan McKee is welcome to moan and groan as much as he likes. Ruth and all the Scottish conservative team will get on with delivering a positive message for Scotland at conference this week.”