The duo are a 31-year-old man from Kajang, Selangor, and a 42-year-old Chinese national, said Kuala Terengganu police chief Azli Noor.

Azli said police received a report regarding the incident at about 12.45pm, and a boat from the Terengganu fisheries department, with seven rescue divers from the police and the marine park, was deployed for a search operation at 2pm.

The operation was also assisted by seven volunteers from a resort using two of their boats.

He said it is understood that one of the missing men is a dive master while the other is a student diver.

Azli said the search operation also covered the surrounding areas of Pulau Bidong, Pulau Geluk and Pulau Tengkorak.

He said the operation had to be suspended at 6pm because of rough sea conditions, and will resume tomorrow morning.