A helicopter headed for an oil platform with 21 people on board crashed off the coast of Terengganu.

Twenty people, including 19 oil rig workers and the co-pilot, were rescued but the 48-year-old pilot was still missing.

Terengganu state police chief Acryl Sani Abdullah Sani said the helicopter is thought to have experienced technical problems and crash-landed about 200 metres from a platform belonging to US oil giant ExxonMobil.

"The colleagues of the workers on the platform realised what had happened and immediately launched a rescue operation," he was quoted as saying by the national Bernama news agency.

In search of pilot

The crash occurred in the early afternoon some 113 nautical miles from the coastal town of Dungun, a local police officer sadi.

"Thirteen passengers were injured," he added.

Three of the workers are believed to have been flown to a hospital in the state's capital of Kuala Terengganu, said Bernama.

Acryl said Malaysia's Maritime Enforcement Agency was searching for the pilot.