A Malaysian tugboat was attacked by gun-wielding pirates in the Malacca Strait in what is said to be the first incident for the year, and following the deadly tsunami disaster, said an official.

"Pirates fired at the tugboat and boarded it. They kidnapped the Malaysian captain and Indonesian chief officer," Noel Choong, regional manager of the Piracy Reporting Centre of the International Maritime Bureau, told AFP .

"They mercilessly shot the chief engineer in the leg, he experienced profuse bleeding," he said.

"It is not known whether it happened in Malaysian waters or Indonesian waters," he said.

The incident happened Monday over 50 nautical miles off Penang in the northern end of the Malacca Strait, he said.

The Highline 26 ship, operated by Sarawak-based Highline Shipping company, was towing a coal-laden barge and heading towards Lumut in northern Perak state where Malaysia's naval base is located.

Same modus

"The modus operandi is similar to the previous attacks that happened in the north of Aceh, or off the coast of Sumatra in Malacca Strait. We believe the same gang of pirates have begun their attacks again," Choong said.

"They would come to the boat and fire at the ship. They normally take the ship engineer but realising that he was seriously hurt, they took the chief officer instead," he said adding that the pirates did not loot the cargo.

The pirates damaged all communications equipment and escaped after kidnapping the two, he said.

"We believe the pirates have escaped into Indonesia," he said.

A passing naval ship had provided initial assistance to the tugboat. Marine police then escorted the ship to northern Penang island, he said.

"Investigations are ongoing," he said.

The waterway bordered by Malaysia, Singapore and Indonesia is used by some 50,000 ships a year carrying a third of world trade and half its oil supplies.

Thirty mariners were killed worldwide last year in pirate attacks including four in the Malacca Strait, the Piracy Reporting Centre said in its annual report last month.

Since late 2003, there had been a steady increase in attacks and kidnappings in the strait and along the coast of Aceh, where a separatist revolt is being waged.

But pirate attacks had halted since the tsunami that devastated the region in December.