Five men carrying rifles, pistols and a grenade launcher boarded the boat at sea and ordered others on board - a policeman, a town councillor, and the vessel's skipper - to jump off, Sadikul Sahali, governor of the southernmost Philippine island of Tawi-Tawi, told reporters.

The gunmen then sped off with their hostages -- Dutchman Elwold Horn, 52 and Swiss national Lorenzo Vinciguerra, 47; and their guide, regional police chief Bienvenido Latag said.

"This is the fault of their guide, he did not want to coordinate security with our authorities," Sahali said. The tourists, he said, had wanted to view endangered bird species.

No group has claimed responsibility for the abduction, but kidnapping for ransom is common in the southernmost islands of the Philippines, where a number of Muslim rebel groups operate.

Among them are the small but violent Islamic militant group Abu Sayyaf and the largest Muslim rebel group, the Moro Islamic Liberation Front MILF.L.

The United States, Britain and Australia have advised their citizens not to travel to these areas.

Officials believe the al Qaeda-linked Abu Sayyaf is holding a retired Australian soldier taken at gunpoint in December from his house in the southern province of Zamboanga Sibugay. He appeared in a video last month saying his captors were demanding $2 million in ransom.

(Reporting by Rosemarie Francisco; Editing by Ron Popeski)

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