PHILADELPHIA (AP) _ Two laboratory workers suspected of selling human body parts to a Philadelphia physician have been suspended by the University of Pennsylvania Medical Center, which also is ending its hospital ties with the specialist.

''We are deeply disturbed that people associated with the medical center may have violated both their professional trusts and common rules of human dignity,'' Dr. Laurence Earley, senior associate dean at the university's medical school, said Monday.

The university issued a statement saying Dr. Martin Spector, an ear, nose and throat specialist who had admitting privileges at the Hospital of the University of Pennsylvania, was being informed of his immediate suspension of affilation with the hospital.

Spector is being investigated in connection with the shipment of five human heads to a Colorado research center.

No charges have been filed against Spector or the laboratory workers, whose names are being withheld by authorities.

One of the workers has denied selling body parts to Spector, police sources told The Philadelphia Inquirer. Three current and past employees of Spector said they did not recognize that employee, but said they often saw the other suspect, according to the paper.

''The medical center will appoint a panel to review the entire situation and institute additional safeguards,'' Earley said.

The investigation began after United Parcel Service workers in Louisville last month discovered heads in a leaky box bearing Spector's return address. The workers forwarded the box to the Colorado Research Center in Denver, authorities said, but officials at the center say the heads never arrived.

On Monday, UPS spokesman Ken Sternad said workers at the Louisville air hub returned the heads they discovered to Spector's Philadelphia office.

One of the Penn laboratory workers has told police Spector paid $150 for each head and $65 for each arm taken from corpses at the medical center, according to police sources.

The Penn employee told police he has known Spector for about 10 years and has been selling him body parts for up to four.

Police said the body parts apparently came from unclaimed corpses or from bodies donated to the university's medical school for use in training students.

The two Penn employees would put the heads and arms in their cars and drive to the doctor's office, the sources said. Spector paid the workers in cash, according to the sources.

Spector has told police that he has shipped body parts for 15 years, according to District Attorney Ronald Castille. The Colorado Otologic Center, a non-profit research institute, reported receiving three shipments from Spector over the past nine months.

Spector's lawyer, Edward T. Feierstein, has said the doctor broke no law.

The state health code stipulates that cadavers of Pennsylvanians may not be shipped out of the state for medical research. The health code also requires that parts of cadavers donated to medical schools for research be kept together and then cremated and buried in a dignified manner.

Violations of the health code are not criminal offenses but are grounds for reviewing a doctor's license.

Castille said dealing in body parts would appear to violate state laws against abuse of a corpse.

Spector, who has refused to comment since the shipment became public, was unavailable for comment Monday, his answering service said.