Argentine authorities have ordered the body of Christina Onassis held in Buenos Aires pending new medical tests examining the possibility that the shipping heiress died of a drug overdose.

Buenos Aires Judge Juan Carlos Cardinali said Monday that medical experts so far have found no evidence that Onassis' death, caused by an excess of fluid in the lungs, was drug-induced.But he said further tests were necessary to remove all doubt.

Another magistrate, Federal Judge Alberto Piotti of the San Isidro district, said Monday the body has "been interdicted" until an investigation has determined whether "the utilization of a drug" caused the death.