Singer Chris Brown has pleaded not guilty to charges arising from an alleged attack on his girlfriend, the R&B star Rihanna.

Reuters reports that Brown entered the pleas during his arraignment in the Los Angeles Superior Court; he is due back in court on 29 April.

Rihanna's attorney told the press that his client hoped that a plea bargain could be agreed but that she would testify against Brown if required.

Brown and his attorney made no comment to the media.

He is accused of assaulting Rihanna "by means of force likely to produce great bodily injury" and threatening to commit a crime "which would result in death and great bodily injury".

Brown faces up to four years in jail if convicted.