Naval forces have been sent to track down pirates who kidnapped three crewmen of a Malaysian tugboat and are believed to have fled to the southernmost Philippine islands, officials said today.

"Our naval units are checking the islands" of Tawi-tawi archipelago said Commodore Rufino Lopez, chief of regional naval forces in the southern Philippines.

The navy identified the three Indonesian hostages as tugboat captain Ahmad Rumiyati, 33, Yamin Labusu and Erekson Hutagul. They were seized when five rifle-wielding pirates boarded their vessel, the Bonggaya 91 tugboat, off Sabah on Wednesday.

Lopez said the pirates, who are believed to be Filipinos, took their hostages on a speedboat towards Tawi-tawi.

"The Philippine navy is coordinating with the Malaysian police regarding the incident," said navy spokesman Captain Geronimo Malaban.

Previous cases

Authorities suspect the abduction may be the work of the Abu Sayyaf, a Filipino Muslim extremist group that has engaged in kidnapping and bombing attacks mostly in the southern Philippines for over a decade.

Last year Abu Sayyaf kidnappers seized three seamen - two Malaysians and an Indonesia - who were discovered early this year to have died in captivity.

Abu Sayyaf kidnappers also seized 21 Western tourists and Malaysian and Filipino resort workers from resorts in Sipadan in Malaysia in 2000. Most of the hostages were freed after ransom was paid.

The extremist group has been linked by the United States and the Philippines to the al-Qaeda network of Osama bin Laden.