Los Angeles  - Chris Brown was dumped by two major advertisers Tuesday after his arrest for allegedly beating girlfriend Rihanna just before the Grammy awards.

The District Attorney's Office meanwhile ordered police to continue investigating the incident before deciding what charges to press against the 19-year-old star whose first court appearance is set for March 5, the Los Angeles Times reported.

Thus far Brown has been charged with making criminal threats and is free on bail of 50,000 dollars. But legal observers said the instructions for continuing the investigation made it likely that Brown could be charged with more serious crimes.

The development came as more details emerged about the violent altercation, and as music stars said they were shocked and devastated over Brown's behaviour.

People Magazine quoted police sources and a friend of the couple as saying that Rihanna needed medical treatment after the assault.

"Chris knocked her around," a source close to the couple told People. "Black eye, blood, bruises. She had to be treated by a doctor."

Rihanna is cooperating with police in the investigation of Brown, the Los Angeles Times reported.

The incident has caused both Brown and Rihanna to cancel scheduled appearances. Brown pulled out of the NBA All Stars Game this weekend in Phoenix, Arizona, while Rihanna scrapped a concert scheduled for Friday in Malaysia, E! Online reported.

Wrigley's said that it had suspended its chewing gum ads featuring Brown, because of its concern over the case. Brown was also suspended from the famous "Got Milk" ad campaigns which feature celebrities sporting a milk mustache on their upper lip, according to gossip magazine Us Weekly.

"The Milk Mustache campaign is taking the allegations against Chris Brown very seriously. We are very proud and protective of the image of the Milk Mustache campaign and the responsible message it sends to teens," the campaign was quoted as saying.

Rapper Kanye West said he was devastated by reports of the incident. "I was completely devastated by the concept of what I heard," Kanye said in a radio interview Tuesday.

While proclaiming her to have the potential to be the "greatest artist of all time," West said that his reaction superseded her status. "I don't care how famous she is or even if she just worked at McDonald's, that should never happen. It should never come to that, to that place," he said.

But rapper T. I., who himself is facing a prison term over weapons charges, indicated that Brown was not taking the incident too seriously. T. I. told US talk show Last Call with Carson Daly that he spoke to Brown on Monday about the situation.

"He's cool, you know. He's a little concerned about the situation, but he's still the same Chris," T. I. said. "I told him, 'This too shall pass.'" (dpa)