The first minister has already said he will not suspend his predecessor after she was arrested and later released without charge following a police probe into the SNP's funding and finances.

Following Ms Sturgeon's arrest, former SNP leadership candidate Ash Regan and SNP MSP Michelle Thomson both called for the 52-year-old to resign the party whip.

SNP MP Angus MacNeil also called for "political distance" amid the "soap opera", claiming Ms Sturgeon "suspended others from the SNP for an awful lot less" during her time in charge.

Speaking to journalists at Holyrood on Tuesday, Mr Yousaf said there was no pressure for Ms Sturgeon to resign.

He added: "I will speak to our group. I think it's important that we have a unified voice in these matters. But I'm not going to stop MSPs from expressing their view - that is entirely their prerogative."

Ms Sturgeon was arrested on Sunday and questioned for around seven hours as part of Operation Branchform.

The long-running Police Scotland inquiry is linked to the spending of around £600,000 raised by SNP supporters and earmarked for Scottish independence campaigning. It is understood there have been complaints the ringfenced cash has been used improperly by being spent elsewhere.

Ms Sturgeon, who has denied any wrongdoing, is the third high-profile SNP member to be arrested in connection with the probe.

Her husband, ex-SNP chief executive Peter Murrell, and former SNP treasurer Colin Beattie were both arrested and later released without charge back in April.

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Mr Yousaf denied being "weak" for not taking action against Ms Sturgeon, who he described as Europe's "most impressive" politician.

He said: "I have shown consistency throughout this process.

"People are released without charge - there's no reason to suspend them, I've made that clear. It's the way I've treated other parliamentarians, for example, and that's the way I'll continue.

"I know why the opposition want rid of Nicola Sturgeon out of here, because, of course, she's thrashed them at every single election. So, hardly surprised at that."

The first minister said he had not spoken to Ms Sturgeon since her arrest.

He added: "It's a very, very difficult time for her and a difficult time for our party, and personally painful to many of us too."