He was found lying unconscious in the cell at about 4.59am and was confirmed dead by a medical officer from Shah Alam Hospital at about 5.20am, federal police headquarters said.

An autopsy is scheduled to be held tomorrow to determine the cause of death, a police spokesman said. The case has been classified as one of sudden death and an investigation would be conducted by the integrity department and the death in custody unit.

The man had been arrested under the Dangerous Drugs Act on July 29 and placed in the lockup while investigations were being carried out.