Malaysian marine police were hunting for a tugboat and a barge it was towing after they and the Indonesian crew were hijacked by pirates in the South China Sea, officials said.

"We have issued an alert to our men to be on the lookout for the hijacked tugboat in our waters," southern region deputy marine police chief Omar Dawam told AFP .

However, he said the pirates and the Malaysian-owned tugboat were believed to be in Indonesian waters.

Ships plying the Malacca Strait have also been instructed to inform the police if they sight the hijacked vessels.

A gang of three pirates hijacked the "Zara" tugboat and the "Zara 3" barge on Tuesday several hours after the vessels had left southern Johor state for Labuan, in eastern Sabah state, off Borneo island, said Omar.

Men wearing masks

The barge was carrying three containers of oil platform machinery spare parts worth RM1.8 million and had entered Indonesian waters in the South China Sea when it was attacked, he said.

"Three men wearing masks and armed with machetes hijacked the tugboat. During the incident, one of the crew members were hurled into the sea," he said.

Malaysian John Balang, 33, was later found and rescued by the Indonesian navy, said Omar.

It was not clear why the pirates had thrown him overboard.

The pirates, who were believed to be Indonesian, then fled with the tugboat and the remaining eight crew, who were also Indonesian, he said.

The ship's owner in Sibu, eastern Sarawak state, had not yet received a demand for ransom, he said.