Six rebels and a pro-government militiaman were killed while another militiaman was wounded during the five-hour gunbattle on Friday, said the military, adding the attack only ended after they deployed helicopter gunships.

Around 60 fighters of the New People's Army (NPA) attacked the outpost on the southern island of Mindanao in an effort to capture the base, said military spokesman Lieutenant Colonel Ramon Zagala.

"Their objective was to overrun the detachment and get the firearms and ammunition for themselves," he told.

Two MG-520 attack helicopters were sent to drive back the guerrillas, he said.

This is part of an insurgent strategy of using large-scale attacks to capture remote and vulnerable outposts, Zagala said.

"They have increased their tactical offensives and we were expecting that. These violent acts are to show they are still a force to be reckoned with," he added.