Motown legend Smokey Robinson is under criminal investigation in Los Angeles over accusations of sexual assault.

The Los Angeles County Sheriff's Department confirmed it had launched a formal inquiry into the allegations, saying the probe was in the "early stages".

The investigation comes after a lawsuit was filed last week by four anonymous housekeepers against the 85-year-old singer-songwriter, accusing him sexual battery, false imprisonment, negligence and gender violence.

Mr Robinson has denied the allegations. His lawyer has said those behind the accusations are after the musician's money, and he welcomed the police investigation "because exposure to the truth is a powerful thing".

"We feel confident that a determination will be made that Mr Robinson did nothing wrong, and that this is a desperate attempt to prejudice public opinion and make even more of a media circus than the Plaintiffs were previously able to create," the attorney, Christopher Frost, said in a statement to the BBC.

He argued the police investigation was only opened because the plaintiffs filed a formal report with their allegations and said the claims were "manufactured" and designed to "tarnish the good names" of the musician and his wife, who is also named in the lawsuit and accused of contributing to a hostile work environment.

The sheriff's department told the BBC in a statement that its Special Victims Bureau was "actively investigating criminal allegations involving William Robinson AKA 'Smokey Robinson.' The investigation is in the early stages, and we have no further comment."

The women filed a lawsuit in Los Angeles Superior Court on 6 May under the pseudonyms Jane Doe 1, 2, 3 and 4.

In the 27-page legal action, they allege several incidents that they say dated back to 2006, and accuse Mr Robinson of pressuring them into sex.

All four women, who are of Hispanic descent, said they had not come forward until now because they feared losing their livelihoods, familial reprisal or embarrassment. Some were concerned the allegations could affect their immigration status.

They are seeking at least $50m (£38m) in damages and a jury trial.

Mr Robinson was Motown's first hitmaker, writing number one records like Mary Wells' My Guy and The Temptations' My Girl.

He was both a talent scout for the record label and one of its most prominent recording artists in his own right, known for songs like Tracks of My Tears, Shop Around and Tears of a Clown.

He has spots in both the Rock & Roll Hall of Fame and the Songwriters Hall of Fame, and claims to have credits on more than 4,000 songs.

The women's lawyers held a press conference last week after filing the lawsuit, accusing Mr Robinson of being a "serial and sick rapist" who "must be stopped".

Mr Robinson's legal team called the event a "bizarre" attempt "to enlist the public as an unwitting participant in the media circus they are trying to create".

"We will have more to say in the coming days as we make our legal response, and in time Mr Robinson will respond in his own words," Mr Frost said, noting that the musician's legal team plans to ask for the case to be dismissed.

"We ask anyone following this case to reserve judgment as the evidence comes to light and all the actual facts of the case unfold."