Two male nurses in Uruguay were charged with involvement in at least 50 suspicious deaths in separate hospitals in the capital, Montevideo, a news report said.

Police said they suspected the men acted independently and could have killed as many as 200 people, El Pais newspaper reported online late Sunday.

The suspects, aged 39 and 46, confessed to killing a total of 16 people over the past two years by injecting them with morphine and air, police were quoted as saying.

An investigating judge on Sunday charged the two with aggravated murder. A woman, reported to be another nurse and the wife of one of the suspects, was also arrested for having knowledge of the deaths.

The accused said they acted on compassionate grounds, the report said. But the authorities said they suspected the reason was the burden of looking after the patients.

All were in intensive care units but none had been in immediate danger of death, the report said.