Chris Brown fears he will be mobbed by fans at a charity event in Los Angeles today (22.12.13).

The 'Fine China' hitmaker, who has been granted special permission to leave rehab 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, has urged his supporters not to cause chaos by loitering in the area.

The 24-year-old star wrote on Twitter on Saturday (21.12.13): ''To all the fans and supporters coming to the toy drive we ask that u please not loiter as well as park in front of the establishments. Thx (sic)''

He added: ''Thx for understanding. See you tomorrow (sic)''

A source previously revealed that Chris was warned he would be kicked out of rehab if he stepped out of line at the charity drive, and he must return immediately to his treatment facility afterwards, where he will undergo a drug test.

Chris was ordered to seek help to manage his anger by a judge shortly 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His probation, stemming from a violent assault on his ex-girlfriend, Rihanna, in 2009, was revoked after he got into a fight in Washington DC in October.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 treatment.