Five bodies have been recovered at the scene of the fighting, Philippine military spokesman Brigadier-General Restituto Padilla said on ABS-CBN television in Manila.

At least one policeman was confirmed killed in the fight, national police spokesman Senior Superintendent Dionardo Carlos said in a statement.

"Security forces reported that the armed group is well-armed with heavy-calibre weapons, but now cornered in an isolated section" of Bohol, Philippine military chief of staff General Eduardo Ano said in a statement.

The incursion would be the first on the tourist island by the Abu Sayyaf, which has long engaged in kidnapping for ransom -- often targeting foreigners.

The group, also blamed for deadly bombings, has pledged allegiance to the Islamic State movement that holds large swathes of Iraq and Syria.

The gunmen sailed into the Bohol town of Inabanga on Monday, going upriver toward a remote section of the island aboard three fast boats, Inabanga police officer Edwin Melicor told AFP by telephone.

A clash broke out as police went to investigate early Tuesday, Melicor added.