Chris Brown has been warned he will be kicked out of rehab if her misbehaves tomorrow (22.12.13).

The 'Fine China' singer has been granted special permission to leave his treatment facility for a few hours to help collect Christmas toys for underprivileged children at a drive hosted by his clothing line, Black Pyramid, and skateboard company, Brooklyn Projects, on Melrose Avenue, in Los Angeles.

A source told gossip website TMZ.com that the 24-year-old star will be kept on an extremely tight leash at the event and has been told he will be kicked out of rehab for good if he steps out of line.

Chris, whose doctors believe the experience will be good for his treatment, only has permission to attend the event from 1pm until 4pm tomorrow, and he must return immediately afterwards.

The facility is giving him just enough extra time to travel to and from West Hollywood, and if he is late back on Sunday evening, he will be kicked out.

He will also undergo a drug test when he returns from the event.

Chris was ordered to rehab by a Los Angeles judge soon after he was kicked out of another centre in Malibu, California because he threw a rock through his mother's car window.

His probation, stemming from a violent assault on his ex-girlfriend, Rihanna, in 2009, was revoked after he got into a fight in Washington DC in October.

Rather than being sentenced to jail, however, the judge is allowing the singer to complete his rehab for anger management.