Singer Chris Brown has pleaded guilty to assaulting pop star and former girlfriend Rihanna.

Brown was sentenced to five years probation and six months of community service - cleaning up graffiti and roadsweeping.

Los Angeles Superior Court Judge Patricia Schnegg also imposed a court order requiring Brown and Rihanna to stay at least 45 metres from each other, except at industry events when the distance is reduced to nine metres.

Brown's plea to a felony charge will subject him to substantial scrutiny by probation officials, and the judge's order rules out any short-term prospects for reconciliation.

Mark Geragos, Brown's lawyer, said the plea represented the singer taking responsibility for his actions - which included beating, choking and biting Rihanna during a fight early on February 8, according to police.

Brown was arrested in February, hours after police say he hit and threatened Rihanna after leaving a pre-Grammy party.

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