American R&B star Chris Brown, who was convicted of assaulting his then-partner Rihanna in 2009, was at the centre of a new police investigation Saturday for alleged battery, US media said.
The TMZ celebrity website cited the alleged victim as saying that Brown punched her in the face at a private party in his suite at a Las Vegas hotel early Saturday after she took a photo of him.
TMZ quoted a representative for Brown saying that the claims were "undeniably untrue".
Police were investigating the allegation, TMZ and other US media said.
There was no immediate public reaction from the singer.
In June 2009, Brown pleaded guilty to assaulting pop star Rihanna, who suffered facial injuries and was forced to cancel an appearance at that year's Grammy Awards.
Brown was sentenced to five years' probation, a yearlong domestic violence program and 180 days of community labour.