PHILIPPINE police have launched an investigation into alleged drug links between at least five ranking officials of the Philippine National Police (PNP) and a Hongkong triad gang. The investigation was launched after senator Vicente Sotto charged that active and retired officials were protecting a large Manila-based syndicate which was bringing ice (methamphetamine hydrochloride) into the Philippines. Mr Sotto, vice-chairman of a senate committee on illegal drugs, has produced documents from US officials indicating the syndicate imports 200 kilograms of ice a week into Manila. The syndicate was reported to have had plans to open an ice processing laboratory. Mr Sotto did not identify the Hongkong triad. He only said it was among the most notorious in Hongkong and that four members were in Manila as ''managers''. Mr Sotto said the role of the police was to act as ''advisers'' to the Hongkong end of the syndicate, pointing them to safe drop-off points. The drugs were smuggled through the Ninoy Aquino International Airport, two ports in Manila, and the Mactan International Airport in Cebu, he said. Mr Sotto has also implicated two retired police generals, several PNP officials in the narcotics command unit, customs officials and members of the Philippine Aviation Security Command. Because of his revelations, Mr Sotto, a former movie star, claims to have received at least one death threat last week.