Western Cape police are investigating an allegation of sex with a corpse at Salt River Mortuary, and the amputation and theft of a foot from another body.

And a reliable mortuary source said the sexual assault on a young male was "just the tip of the iceberg" and "several more young male corpses have been violated".

Two "crime against a body" cases linked to the state mortuary have been opened at Woodstock police station.

The alarm was raised after police staff at the Durham Road mortuary found that the body of a young suicide victim had been sodomised last month.

Then the foot was sawn off the body of a man who died in a southern suburbs road accident at the weekend.

It is still missing.

Investigators are focusing their inquiries on staff at the morgue, but they have not ruled out the possibility that the suspect or suspects could have been visitors - civilians or even police from other units.

Provincial police spokesperson Riaan Pool confirmed on Thursday that the theft of a body part was being investigated.

He also confirmed the necrophilia investigation, but described it as "precautionary".

The investigation was launched after a policeman found a body bag unzipped and evidence of a sexual assault.

Forensic pathologists were called in and took body fluid and human tissue samples from the dead man for testing and DNA sampling.

In the case of the sawn-off foot, mortuary pathology instruments were confiscated and sent for forensic examination.

Pool said senior police and social workers had been in contact with the family of the accident victim to inform them of the incident and to keep them up to date with the progress of the investigation.

He said that in the other case the victim's family would be contacted after police had established "beyond all reasonable doubt" that the corpse had been sodomised "post mortem".

A long-serving police officer attached to the mortuary said that in an incident in 1989 mortuary staff had caught a half-naked policeman on top of a female corpse.

He said no criminal case had been opened, but the officer had been transferred to a police station the next day.

The police watchdog, the Independent Complaints Directorate, has been told about the latest investigations but is not yet involved.

Provincial department of health spokesperson Faiza Steyn said she was deeply shocked and disgusted by the discoveries and extremely concerned for the families of the dead. "We are there to serve the community. It is a shock," she said.

"The mortuary is a department of health facility, but its staff, who are police members, fall under the police."

"I'm waiting for a report on the incidents," Steyn said.