Douglas Ross’s position as Scottish Tory leader has been “significantly undermined” after he chose to stand as a General Election candidate over colleague David Duguid, John Swinney has said.

The Scottish Tory leader has faced criticism after he announced his candidacy in the Aberdeenshire North and Moray East constituency last week after Mr Duguid was blocked over health concerns.

Mr Duguid had hoped to contest the seat, which replaced his previous Banff and Buchan and part of Mr Ross’s former Moray constituency under new boundary rules.

However, Mr Duguid is currently in hospital after becoming unwell in April and said the party’s membership candidate had de-selected him as a candidate.

Mr Ross previously said he would not contest his seat at the General Election, instead promising to focus on his MSP role and leadership responsibilities.

While Mr Ross has defended his position to stand, citing the “very unique circumstances” around Mr Duguid’s health and the timing of the election as his motivations, SNP leader and Scottish First Minister John Swinney accused his opponent of “naked self-interest”.

He said: “I think his ability to continue as Scottish Conservative leader is significantly undermined by his behaviour.

Douglas Ross has no credibility whatsoever

“Douglas Ross has no credibility whatsoever – he has been telling us all that he wants to be leader of the Scottish Conservative Party so that he can become the first minister of Scotland.

“But he is now taking a decision to try to get back to the House of Commons so he is just exercising constant naked self-interest in the decisions that he takes.”

Mr Duguid has denied claims he is “unable to stand” in the election.

A Scottish Conservative spokesperson said: “The party management board took an incredibly difficult decision to conclude that David Duguid could not stand at this election for health reasons.

“David has been a fantastic local MP for the last seven years and Douglas worked incredibly well with him as the neighbouring MP in Moray.

“Everyone wishes David well in his continued recovery and looks forward to his return to frontline politics.

“Given the short timeframe to ensure we had a candidate in this key seat, Douglas decided he needed to lead from the front and stop this area being represented by an SNP MP who would only focus on independence, rather than local people’s real priorities.”