Chris Brown has publicly apologised for beating up ex-girlfriend Rihanna.

The R&B singer posted a two-minute video on his website last night expressing his regret about the attack and telling his fans that he is sad and ashamed of his conduct.

Brown was arrested February 8 and later charged with assault likely to cause great bodily harm. He pleaded guilty to the assault charge last month and faces sentencing on August 5.

He could be made to serve five years of probation and perform six months of community work.

Dressed in a long sleeve red shirt and looking directly at the camera, Brown said he had apologised to Rihanna several times.

He said: "I've told Rihanna countless times and I'm telling you today, I'm truly, truly sorry that I wasn't able to handle the situation both differently and better."

Brown says on the video he wanted to speak out earlier, but his lawyer advised him against it.

He expressed his "deepest regret" over the incident and said he "accepts full responsibility", telling viewers that he wishes he could "live those few moments again", because he was taught "better than that."

He said: "I intend to live my life so that I am truly worthy of the term 'role model."