Philippine troops captured an Islamic militant training camp after a 10-day battle, officials said, as part of operations to clear insurgents from a remote jungle region.

The offensive against the Maute group, one of several Filipino Muslim armed organisations which have pledged allegiance to the Islamic State, left four soldiers dead and 15 others wounded, a Philippine military commander told an AFP photographer at the scene.

Surrounded by swamps and a lowland tropical rainforest in the small, Muslim-populated farming town of Butig, more than 800 kilometres (500 miles) south of Manila, the camp's structures were riddled with large bullet holes that soldiers said were caused by machine gun fire used to flush out the militants.

Soldiers said they killed dozens of militants, but there was no sign of dead bodies when the military allowed journalists into the area on Friday.

Unexploded improvised explosive devices, a grenade launcher, a rebel uniform and a black Islamic State flag were all that were left in the wooden huts and concrete-reinforced trenches, which were used by the gunmen, army Colonel Roseller Murillo said.

"The Maute group is believed to be on the run and in hiding, (but) the military will fully enforce the law if they initiate other terrorist activities in the area," he told AFP.

The offensive was launched after the militants moved back into territory that the military secured during clashes in February, they said.

Once described by the military as a small-time extortion gang, the Maute group attacked a remote army outpost in Butig in February, triggering a week of fighting that the military said left six soldiers and at least 12 militants dead.

The group, believed to have fewer than 100 fighters, blew up power transmission towers and abducted and beheaded two employees of a local sawmill in April.

Murillo said the latest military offensive began on May 24. The fighting displaced about 2,000 residents, according to the military.

The southern Philippines has been plagued by a Muslim separatist insurgency for over four decades, with the conflict leaving more than 120,000 dead.