Police in Las Vegas are investigating a woman's claim that she was attacked by Chris Brown after she tried to take a photo of the R&B singer.

Lt Jeff Goodwin said authorities received a call shortly before 10.30am local time on Saturday about the alleged assault at the Palms Casino Resort.

A police statement said an altercation took place in a room at the resort when the woman went to take a picture of Brown, 26.

The woman said she was struck by Brown and that he had taken her mobile phone. Detectives tried to speak to Brown at his hotel room, but the singer left before police had arrived.

Police said a crime report has been taken for misdemeanour theft and battery listing Brown as a suspect.

Brown's publicist Nicole Perna described the woman's claims as "unequivocally untrue".

The singer performed on Friday at Drai's nightclub at The Cromwell Las Vegas, where he appears regularly.

In December Brown cancelled plans for a Down Under tour after Australian authorities warned him that they were likely to refuse him a visa because of his criminal conviction for assaulting his former girlfriend, pop star Rihanna.

He pleaded guilty to felony assault after the brutal attack, which happened hours before the Grammy Awards in 2009, and was freed from probation last year.