HUMZA Yousaf has appeared to accuse his two rivals in the race to become the next SNP leader of “baseless smears” after they both called for independent auditors to be brought in to oversee the ballot.

On Wednesday evening, both Kate Forbes and Ash Regan called for the SNP to “appoint a robust, experienced, third-party auditor of both the ballot processes and the eventual tally of the vote”.

It came after all three camps, and a host of parliamentarians including senior MPs Ian Blackford and Pete Wishart, called on the SNP HQ to publish the party’s membership figures.

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The SNP initially refused to bow to the pressure, but it is understood that the ruling National Executive Committee is to be asked their views Thursday. It is expected they will agree to publish the data.

Regan has issued an ultimatum to the party, saying she will hold a press conference about the situation outside Holyrood at 3pm if her concerns have not been satisfactorily addressed by then. 

Michelle Thomson – who is running the Forbes campaign – said some concerns are “based on hearsay or are from bad faith actors”, but she added: “However, others are being openly expressed by individuals within the SNP of longstanding.”

Amid the row, SNP president Michael Russell said he had made it clear to party chiefs that he supported publishing the membership figures – but he cautioned against questioning the validity of the ballot.

Russell said he had “full confidence in [SNP national secretary Lorna Finn] and the external verification and count”, adding: “I am disgusted by the abuse directed at @theSNP staff by individuals who damage our cause and aid our enemies.”

Responding to Russell’s tweet, Yousaf appeared to take a swipe at his rivals for their calls for an auditor to be brought in.

He wrote: “I could not agree more. My team has called for publishing membership figures.

“I have confidence in the process that uses an external 3rd party company, a process we have used for many years. I am up for challenge and reform of the party, but let's not indulge in baseless smears.”

Forbes and Regan’s calls for independent auditors to be brought in have split the SNP. Gavin Newlands, the MP for Paisley and Renfrewshire North, accused the Finance Secretary of “Trumpian nonsense”

He wrote on Twitter: “The vote is being carried out by a highly regarded and independent 3rd party. Quite frankly, this is just #fakenews crap. I thought better of Kate's camp.”

His colleague, Glasgow Central MP Alison Thewliss, responded to Regan’s advisor and strategist Kirk Torrance with a GIF saying: “Stop the madness.”

She also retweeted a post which read: “This is exactly how votes for office bearers at conference and candidate selections have been done for years.

“None of these people were concerned when they were being selected. All of a sudden they think the system needs changed in the middle of an election.”

But Edinburgh South West MP Joanna Cherry said the requests were “perfectly reasonable”, adding: “They must be fully addressed today to avoid serious reputational damage to our party.”

The election process is being carried out by Mi-Voice, an election services firm based in Southampton.

John Swinney, the deputy first minister and former SNP leader, told BBC Scotland on Thursday morning that he didn't understand what the argument was about. 

Swinney, who is backing Yousaf, said: “I don’t understand half of these comments.

“The process is being conducted by an independent ballot services company, that is an independent organisation. They have got a professional reputation to deliver ballot services effectively and without question.

“My experience, and I have got a lot of experience of elections within the SNP ... [is that] they have been completely straightforward, efficient, independently organised processes, and this is exactly the same.

“So I don’t know what this is all about.”