A judge has ordered a review of Chris Brown's progress during his probation.

Judge Patricia Schnegg wants to review the singer - who is currently on probation after attacking his then girlfriend Rihanna in 2009 - on November 1 amid concerns about the number of community service hours he has completed and allegations he's violated the terms of his travel restrictions.

But Schnegg has let Brown off with a warning and decided against revoking his probation after he failed a drugs test.

The 'Beautiful People' hitmaker tested positive for marijuana in June in Virginia, where it is illegal, but he since claims to have smoked the drug in California, where he has a medicinal marijuana card.

Before the hearing Rihanna wrote a good luck message to Brown on her twitter account, tweeting: ''@chrisbrown I'm praying for you and wishing u the best today (sic)''

He responded: ''thank u so much (sic).''