Gunmen have abducted a Norwegian resort manager, two Canadians and a Filipino woman from a southern Philippine island.

Two Japanese guests unsuccessfully tried to intervene before the gunmen escaped with their hostages aboard a motorised outrigger from Samal Island off Davao City, said regional military spokesman Captain Alberto Caber.

He said the gunmen appeared to have specifically targeted the victims when they entered the Holiday Oceanview Samal Resort before midnight on the northern tip of the island, about 610 miles south east of Manila.

The kidnap victims are Kjartan Sekkingstad, the resort’s marina manager, and Canadians John Ridsel and Robert Hall.

The Filipino woman is the wife of one of the Canadians.

Davao del Norte provincial police chief Senior Superintendent Samuel Gandingan said the three gunmen were armed with rifles.

In 2001 Abu Sayyaf militants tried to seize hostages from the Pearl Farm Beach Resort south of Oceanview during a ransom-kidnapping spree in the early 2000s in the southern Philippines.

A naval blockade was set up around the island to stop the Samal Island kidnappers from reaching Basilan Island further to the south west, where Abu Sayyaf militants have strongholds where they keep hostages while negotiating ransoms.

Abu Sayyaf, which has about 400 gunmen, was recently declared a terrorist group by a Philippine court and is on Washington’s lists of terror organisations.

The group seized dozens of Filipino hostages on Basilan and 21 people, mostly European tourists, from the Malaysian resort of Sipadan in 2000, and abducted three Americans and 17 Filipinos in 2001 from the Dos Palmas resort in Palawan province south west of Manila.

The militants are still holding other hostages, including two Malaysians, a Dutch bird watcher kidnapped nearly three years ago, and a town’s mayor.

Meanwhile, hundreds of troops have launched an offensive to capture six suspected foreign Islamic militants and their Abu Sayyaf allies in the country's south.

The troops clashed with about 30 Abu Sayyaf gunmen at the start of the assaults near a remote village in mountainous Patikul town in Sulu province.

The militants were laying homemade bombs, one of which exploded, when the troops engaged them, Brig Gen Allan Arrojado said.

The six foreign militants, thought to be from Indonesia and Malaysia, are believed to be providing bomb-making and other assistance to local militants. At least seven Abu Sayyaf commanders were also targeted in the offensive.