Los Angeles  - R&B singer Chris Brown was Thursday charged with assault and making criminal threats, following a highly publicized fight with his popstar girlfriend Rihanna.

If convicted, Brown's sentence could range from probation to more than four years in prison, the Los Angeles County district attorney's office said.

Brown, 19, and his 21-year-old girlfriend got into a fight in a car in Los Angeles before they were to perform at the Grammy Awards on February 8. The reason was text message from a woman that Brown had a pervious sexual relationship with, police said in an affidavit.

The police statement identified the victim as Robyn F - Rihanna's full name is Robyn Rihanna Fenty.

According to the statement, Brown and Rihanna got into an argument over the text message and he tried to push her out of the car.

"Robyn F turned to face Brown and he punched her in the left eye with his right hand. He then drove away in the vehicle and continued to punch her in the face with his right hand while steering the vehicle with his left hand. The assault caused Robyn F's mouth to fill with blood and blood to splatter all over her clothing and the interior of the vehicle," the statement said.

Brown also threatened to kill Rihanna after she faked a call to her assistant. "You just did the stupidest thing ever. Now I'm really going to kill you," the singer said, according to the affidavit.

The document described in detail the brutal manner in which Brown attacked Rihanna - punching her in the face, arms and legs, trying to strangle her, and biting her ears and fingers.

As she screamed for help, Brown got out of the car and a resident from the neighbourhood called the police.

Brown was initially arrested, but later released on a 50,000- dollar bail.

The singer apologized to his girlfriend nine days later, via text message, police said. Some three weeks after the fight, Rihanna and Brown were seen together again.