John Swinney was “genuinely disgusted” by the Tory party’s decision to ditch a seriously ill candidate and replace them with Douglas Ross.

The First Minister said it was “no way to treat another human being" and accused the Scottish Tory leader of "naked self interest."

However, the MSP and now candidate for Aberdeenshire North and Moray East said the “very unique circumstances” meant he needed to put himself forward for the candidacy.

READ MORE: David Duguid denies 'ill-health' claim in Douglas Ross replacement row

On Wednesday night, the party’s Management Board stopped former Scottish Office minister David Duguid from contesting the new seat as they claimed he was too ill.

Mr Ross then announced his intention to “lead from the front” and stand instead.

However, Mr Duguid, has insisted that the party’s claims he is “unable to stand” due to ill health are “simply incorrect”.

Instead, he said it was the party management board “that decided not to allow me to be the candidate, although none of them had visited me”.

He wrote: “They apparently took this decision based on two visits from the party director and without receiving any professional medical prognosis.”

Speaking to journalists at a campaign stop in Springburn in Glasgow, Mr Swinney was asked for his reaction to the Tory party’s decision. He hit out at the “naked self-interest of Douglas Ross.”

“I genuinely was disgusted by what I witnessed.”

“What has happened is the most despicable way to treat somebody who's facing illness, an absolutely despicable way to treat somebody facing illness.

“And David Duguid is a well respected member of parliament. My Westminster colleagues have a very good relationships with him. And he is a good man.

“And he's facing health difficulties.”

The First Minister said that sometimes people become unwell. He pointed to Richard Lochhead, an SNP minister currently recovering from long-term illness.

“For Douglas Ross to essentially require the removal of David Duguid who was perfectly prepared to stand for election, and whose local association wanted him to do so, just to create a new pathway for Douglas Ross to have a new opportunity is a new low, for evem Douglas Ross.

“So I am disgusted by it. Horrified by it. I think it's no way to treat another human being.”and timings meant the party had just over 24 hours to get another candidate in place, so he decided to put himself forward.

READ MORE: David Duguid: Scottish Tories drop hospitalised candidate

Defending the decision, Mr Ross told the BBC: “I want to lead from the front, this is a really important seat.

“It’s one of the many key seats across Scotland where it is a straight choice between the Scottish Conservatives and the SNP.”

Mr Ross added: “The party management board had to look at the situation right now, the situation with David’s health, his recovery, that was at the heart of the decision the management board took.

“It was a very difficult decision, and I understand how difficult it has been for David, for his family, for his staff. I have been in touch with his office.”

Asked if he has spoken to Mr Duguid since he put himself forward for the seat, Mr Ross said he had “reached out” to him, adding that “he will maybe speak when he is able to and he feels able to speak”.