Humza Yousaf told his MSPs they should quit the SNP if they refuse to give their full backing to Nicola Sturgeon following her arrest by police investigating the party’s finances, according to reports.

The first minister said during a private meeting of his party's group at Holyrood that anyone who fails to publicly back his decision to allow Ms Sturgeon to retain the whip was damaging the cause of independence, three separate sources told The Times.

Ash Regan and Michelle Thomson, rebels who have both publicly called for Ms Sturgeon to face suspension while investigations are ongoing, were present at the meeting.

“It was a clear display of him trying to show he is not weak by threatening his own MSPs,” said a source.

The discussions contrast with SNP MSPs with Mr Yousaf’s own account of the meeting which took place yesterday.

He told journalists as he left that he “did not read the riot act” to those who disagreed with his decision not to withdraw the whip from Sturgeon.

He said: “I was listening, I was engaged as any good leader would do. I had a really constructive conversation with the SNP group.”

Sources today told The Times he told the meeting that Scotland is closer to independence than ever before and that disunity threatened momentum towards a separate state.

Polls show that support for leaving the UK remains around 50 per cent while backing for the SNP has fallen by around 10 points since the turn of the year before settling since Yousaf took over in April.

In the first meeting of the SNP Holyrood group since Ms Sturgeon’s police interview on Sunday, Mr Yousaf strongly urged his MSPs to band together for the sake of the party while later agreeing to send Ms Sturgeon flowers as a mark of “sympathy” over her arrest.

She was arrested as a suspect in Operation Branchform, which is investigating complaints about how more than £600,000 of money raised through online appeals was spent, and released without charge.

Allies of Mr Yousaf said that he was delivering a message of unity during the meeting that urged MSPs to not air dirty laundry in public. They said that he was focused on SNP politicians not giving opponents ammunition to attack the party.

Michael Matheson, the health secretary, defended Yousaf’s position and said there was widespread backing for the first minister within the Holyrood group.

“We believe the approach that has been set out by the first minister, the approach [that] has been taken to date by the first minister is the correct one, and that we should adhere to the process that we have in the party for determining these matters should there be a need for them to be considered by the appropriate committee within the within the party overall,” he told the BBC’s Good Morning Scotland.

He was also asked that given other parliamentarians in the SNP have been questioned by the police in the past did you send them flowers?

In his answer Mr Matheson mistakenly referred to Ms Sturgeon as being the first minister.

“I am not aware of the circumstances around those issues. I know flowers were sent to the first minister, that there were different circumstances. Individuals’ allegations.

"The allegations against individuals were of a different nature as well and were dealt with in an appropriate way at that stage. But I am not going to rehearse what happened previously in the party, he said.

Other ministers have been privately critical of Ms Regan andMs Thomson, who accused Keith Brown, the SNP party’s deputy leader, of making “categorically untrue” claims over the row.

Ms Thomson had said the former first minister had to be “consistent” as she herself lost the whip in 2015 after stories were published on her property dealings when Sturgeon was party leader.

Mr Brown told the BBC the decision to withdraw the whip had come from Ms Thomson herself. She rejected the claim and told the Daily Record: “I can confirm that this is categorically untrue. This is why I think it important for the former first minister to set out why she deserves natural justice, which she of course does, but others didn’t when she was in charge.”

Mr Brown said: “This was certainly long before I was the deputy leader but I look back and I saw that decision was taken, according to her own statements, by Michelle Thomson herself.”

Craig Hoy, the Scottish Conservative chairman, said: “The SNP’s established precedent – set by Nicola Sturgeon herself – is to remove the whip from MPs and MSPs while they are under investigation.

“Humza Yousaf has suddenly ditched it because he is too weak to take action against the woman to whom he owes his job. So it’s little wonder many of his own MSPs are up in arms at this blatant favouritism towards Nicola Sturgeon.”