Mr Linden stepped down from North Lanarkshire Council and left the party earlier this year.

The Sunday Mail reported that five men have made allegations regarding the former leader, with two speaking to detectives.

Mr Linden told the newspaper he did not accept the allegations which had been made against him.

A Police Scotland spokeswoman said: "Officers are investigating a report of a sexual assault incident having taken place in 2017. Inquiries are at an early stage and ongoing."

Mr Linden stepped down as council leader in July last year amid accusations of groping and sexual harassment, leading to the collapse of his party's administration.

The ex-SNP politician then quit the council in March after fresh claims of misconduct, dating back to 2015.

At the time, Mr Linden said he refuted the allegations and vowed to "robustly" defend himself.

Several councillors have since left the SNP's group in North Lanarkshire to sit as independents.

Handling of complaints

On Saturday, SNP leader and first minister Humza Yousaf was campaigning in Bellshill ahead of a by-election triggered by Mr Linden's resignation from the council.

He said the party would investigate how it handled complaints regarding Mr Linden and admitted the SNP's issues in the area "could have been handled better".

Mr Yousaf added: "We're absolutely holding our hands up - I, as first minister and leader of the party, say that things of course could have been handled better.

"That's why we'll do the investigation."