A white Los Angeles police officer was suspended after being shown on a videotape slamming a handcuffed black teenager on to the back of a patrol car and punching him in the face as he was being arrested.

The videotape of the arrest of Donovan Jackson, aged 16, was shot by a tourist in a motel across the street from a petrol station where Jackson was arrested.

It shows a prone Jackson hoisted to his feet by Inglewood Officer Jeremy Morse and slammed on to the boot of a police car.

The officer put a hand on the back of the teenager's neck, punched him in the jaw and then appeared to choke him. Two officers appear to intervene, with at least one trying to pull away the first officer's arm.

Morse was suspended on full pay and three other officers at the filling station but not relieved of duty.

Joe Hopkins, an attorney for the Jackson family, said the father and son pulled into the station to get fuel and Jackson went to get crisps. The deputies confronted the youth and ordered him against the car.

A deputy grabbed the youth by the neck before the city officers began to beat him, the attorney said.

"In that video the kid is essentially unconscious. He is out of it," Mr Hopkins said.

He said the teenager was seated on the ground before officers began hitting him.

Lieutenant Eve Irvine, for the LAPD, said Jackson had earlier lunged at a sheriff's deputy before the taping began.

Images from the filling station's surveillance cameras will be viewed to determine what happened, she said.

A spokeswoman for the district attorney, Sandi Gibbons, said it was investigating whether police or sheriff's deputies committed any crimes.

Sheriff's spokesman Sgt. Richard Myers said Jackson was "combative" and was subdued with force. He had been booked for assault on a police officer.

The videotape showed a bloody gash over Morse's left ear and he was cut on his elbow and knee, Lt.Irvine said.

The Inglewood officers were assisting two Los Angeles County sheriff's deputies who were investigating a car that had an expired vehicle registration.

Jackson's father Coby Chavis, 41, who was driving the car, was cited for driving with a suspended licence.