Bajan singer Rihanna celebrated her 21st milestone this week with a belated birthday bash in Hollywood, reports reveal.

The pop starlet turned 21 on February 20th, but was forced to postpone her party ideas as a result of her high-profile relationship problems with boyfriend Chris Brown.

To mark the special occasion, Rihanna enjoyed a VIP night on the town with friends, sipping champagne and eating pink birthday cupcakes at celebrity club Coco de Ville.

Despite reportedly reuniting with R&B singer Chris, 19, he was not included in the star's party ideas but sent her birthday gifts last month.

Commenting on the mood of the evening, a source told People magazine: "She looked good and was smiling and laughing."

The troubled couple are reportedly in the process of recording a duet in a Los Angeles studio.

In the meantime, Chris has withdrawn his nominations from the upcoming Nickelodeon Kid's Choice Awards.