An autopsy was performed today on the body of comedian John Belushi, who was found dead Friday in a Sunset Strip bungalow, but the county coroner said the cause of death "has not yet been established."

Los Angeles County Coroner Thomas Noguchi, citing county supervisors' instructions to "confine information to the determination of the physiological cause of death," said in a statement that no more information would be released until further tests are completed. A spokesman for Noguchi's office said detailed tests of tissue would be done over the weekend.

The autopsy, which began at 10:30 a.m., took about 1 1/2 hours. Afterward, Noguchi refused to answer any questions or comment beyond his statement.

Belushi, famed for his role as a fraternity hell-raiser in the movie "Animal House" and for his television work on "Saturday Night Live," was found nude Friday on a bed in a rented bungalow behind the Chateau Marmont Hotel. A hotel gardener who discovered the body said it appeared he had choked on food.

Police Lt. Dan Cooke said the 33-year-old actor apparently died of natural causes. "The detectives have found nothing to make it seem suspicious in any way," he said.

Cooke said Belushi had been dead for two or three hours before his body was found by the gardener and William Wallace, Belushi's physical trainer, at 12:15 p.m. Wallace "tried to administer mouth-to-mouth resuscitation, and the paramedics were called," Cooke said.

Sources in the coroner's office said Noguchi, in declining to comment on preliminary autopsy results, appeared to be trying to avoid further criticism in his handling of a celebrity's death, after public criticism of his statements tying the deaths of movie stars William Holden and Natalie Wood to alcohol.

Noguchi's office has also come under fire for what appeared to be failure to detect the presence of drugs in some death cases and allegedly sloppy handling of evidence.