American R&B singer Chris Brown has pleaded not guilty to threatening and assaulting his girlfriend, fellow music star Rihanna.

The 19-year-old entered his plea in a soft voice while standing alongside his lawyer, Mark Geragos, in a Los Angeles court overnight. His mother sat in the first row, red-eyed.

Within moments of the hearing, a lawyer for Rihanna said the singer was hoping a plea deal could be reached before the case went to trial. "She would be pleased if this was over quickly," attorney Donald Etra said. He reiterated that Rihanna would testify if required.

Brown was charged in March by Los Angeles County prosecutors with felony assault likely to cause great bodily injury and making criminal threats. He was arrested nearly a month earlier after police said he was involved in an early morning altercation with a woman who identified the Run It! singer as her attacker.

Court records list Brown's victim as "Robyn F". Rihanna's real name is Robyn Rihanna Fenty.

Mr Etra represented the 21-year-old Umbrella singer at the arraignment but did not speak during the five-minute hearing. He said afterward that the singer was in "fine spirits" and spending time with her family in Barbados.

Mr Etra said Brown's plea was " totally expected".

If convicted, Brown could be sentenced to probation or nearly five years in prison.

Neither side has publicly discussed Brown and Rihanna's relationship since the incident but there has been discernible fallout and backlash since Brown's arrest.

Neither singer performed at the Grammy Awards hours after the alleged beating and both were also no-shows for the Kids' Choice Awards show March 28.

Sponsors have stopped using Brown, some radio stations have stopped playing his music and some broadcasters have even started playing an anti-Chris Brown song created by the little-known dance group Smoke Jumpers.

Brown left the courthouse with his mother, two bodyguards and an entourage. On his way out, he had to walk through a phalanx of cameras. He was picked up by a car in front of the courthouse.

Mr Geragos offered no comment and quickly left the courthouse with his client.

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