Armed pirates hijacked an Indonesian-owned ship bound for Singapore, ferried it to a port in Malaysia and unloaded its cargo of tin ingots before escaping to Indonesia, an official said today.

A gang of pirates fired at the 649-tonne ship early Friday when it was passing the Lingga islands and boarded it, Noel Choong, head of the Piracy Reporting Centre of the International Maritime Bureau, told AFP .

"They took control of the bridge, ransacked the ship and tied up the crew," he said.

Choong said the Indonesian-owned ship was sailing from Muntok port in Bangka island for Singapore.

Daring sting

Pirates, however, diverted the ship to Malaysia's Port Gudang in southern Johor state, where they unloaded the ingots.

"It is a daring operation to go into a port. It is the work of a professional syndicate. The syndicate may have made prior arrangements for the ship to unload the cargo in Pasir Gudang port," Choong said.

The ship is now in Singapore, he said.

The latest attacks follow seven pirate raids on ships in the Malacca and Singapore Straits since Feb 28.

Last Friday, Malaysian marine police detained seven Indonesians in waters off southern Johor, near Singapore, who were believed to be responsible for a series of attacks.