Former Scottish leader Nicola Sturgeon was detained as part of an investigation into financial irregularities, as per police reports.

Her detention marks the third arrest in the probe, which has shaken up Scotland's political system, long dominated by the Scottish National Party (SNP).

"A 52-year-old woman has today... been arrested as a suspect in connection with the ongoing investigation into the funding and finances of the Scottish National Party," Police Scotland said in a statement.

On his account, a spokesperson for Sturgeon claimed that the former SNP leader voluntarily attended an interview with police.

The police added that Sturgeon was in custody and was being questioned by detectives.

It is worth noting that Sturgeon's husband Peter Murrell, the former chief executive of the SNP, was detained in April as part of the probe.

Police conducted raids at both the SNP headquarters in Edinburgh and the couple's shared Glasgow home at the time, constructing a crime-scene tent in the front lawn.

Murrell has long been the subject of inquiries about the suspected misappropriation of $750,000 ($600,000) in SNP contributions intended to promote the party's campaign for Scottish independence.

Additionally, he neglected to disclose a personal loan of more than £100,000 to the party.

Colin Beattie, the party's treasurer, was also detained in April. Sturgeon made her last appearance in March in front of the Scottish Parliament as First Minister after announcing her resignation in February.

But the police investigation into Murrell, whom she married in 2010, had overshadowed her.

Murrell resigned from his SNP leadership post in March after the party falsely denied to the media that it had lost 30,000 members.

The disclosure came as the SNP held a bitter election to replace Sturgeon as party leader and Scotland's first minister, eventually won by Humza Yousaf.

The scandal has severely undermined the SNP's ambition of an independent Scotland and thrown the party into a state of crisis.

Only about 45% of Scots support their country leaving the UK, according to recent studies. This is the same proportion as in the 2014 referendum, which London claims put an end to the debate for good.

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