Los Angeles Superior Court Judge James Brandlin said Brown must appear in court again on April 5, and ordered him to contact his probation officer within 48 hours, following the prosecution allegations this week.

The R&B singer was sentenced to five years of probation, a year-long domestic violence program and 180 days of community service after assaulting Rihanna on the eve of the 2009 Grammys.

A photo of Rihanna's bruised face triggered shock and anger at the singer. Although he remains on probation, Brown had been repeatedly praised by the judge for complying with the terms of his sentence.

But in court papers filed Tuesday, prosecutors claimed that the singer had failed to complete the community labor as ordered, and was in fact elsewhere on some of the dates he claimed to be carrying out his sentence.

Deputy District Attorney Mary Murray cited "significant discrepancies" and "sloppy documentation" in reports about the 23-year-old's reported community labor work in his native Virginia.

Brown and Rihanna were photographed being clearly intimate and affectionate with each other in public last month, at an NBA basketball game between the Los Angeles Lakers and the New York Knicks in Los Angeles.

The Grammys, the music industry's biggest awards showcase, are scheduled to take place Sunday at the Staples Center in downtown Los Angeles.