BORIS Johnson has been blocked by Ruth Davidson from attending the Scottish Tory party conference in Aberdeen this weekend.

Scottish Tory sources said a number of potential leadership candidates had been “discouraged” from attending the event, which starts on Friday, amid concerns their appearance could distract from party leader Davidson’s return to frontline politics after maternity leave.

Johnson is currently the frontrunner to succeed Theresa May in a Tory leadership contest but Davidson seemed to doubt his chances of success in an interview on STV's Scotland Tonight on Thursday.

She said: “Let’s remember that not everyone people talk about being a frontrunner make it to the starting line: Boris didn’t last time.”

The National previously revealed a discussion about a breakaway party north of the Border is under way among senior figures in the wake of concerns over Johnson.

It has been reported that a motion has been submitted to the party’s spring conference to change its constitution to remove affiliation from UK party. Party member James Robb has submitted it for consideration.

Holyrood Magazine said it understood that Robb is a former SNP Argyll and Bute councillor who resigned from the party after being deselected in 2017

Sources close to Davidson said they did not want the two-day conference to turn into a leadership hustings when the focus should be on Davidson’s return to frontline politics and the launch of a two-year campaign to elect a Tory government to Holyrood in 2021.

Asked on STV about the presence of Michael Gove and Sajid Javid at the conference – Esther McVey will also appear at a fringe event – Davidson said: “There’s a lot of people want to appear at our conference.”

While reiterating her “full support” for May, Davidson added that she would assess of all of the leadership candidates according to three criteria: their ability to strengthen the union, advance Scotland’s priorities, and bring the whole of the UK back together after Brexit.

Gove, who will address the conference on Saturday morning and speak at a dinner the previous night, is regularly cited by senior Scottish Tories as a politician who “gets the union”.

David Mundell previously said Tories in Scotland – including all but one of the party’s 13 MPs – would be lobbying Westminster politicians against Johnson and backing Gove to succeed May.

READ MORE: Senior Scottish Tory confirms talk of split from UK party