Kuala Terengganu police chief Azli Noor said officers from the criminal investigation department were looking into the incident which occurred at the facility about 150m off the coast, Bernama reported.

“At this stage, the case is being investigated as sudden death. However, further investigations are being carried out to determine the cause of the incident.

“If any criminal element is found, the case will be reclassified,” he said.

In the incident which occurred at 12.50pm, the four victims had boarded a lifeboat on the facility to lower themselves to the sea to carry out maintenance work on the platform’s lower section.

However, the boat’s rope or hook was believed to have detached, causing it to plunge into the sea, killing three oil rig workers and seriously injuring one.

The deceased victims have been identified as Ahmad Fiqri Zakaria, 38; Faezuan Hakim Bustamam, 28; and Nik Hafifi Asri Ab Majid, 38.

Taufik Ruslan, 37, is being treated at Sultanah Nur Zahirah Hospital.