MANILA - Philippine soldiers on Thursday killed 11 members of a Moro guerrilla faction, an Army commander said, underscoring volatility in the resource-rich south of the country as a new government seeks ways to end decades of conflict.

Troops battled rebels of the small but violent Bangsamoro Islamic Freedom Fighters for hours on Mindanao island and a 15-year-old girl was caught in crossfire and killed, said Colonel Cirilito Sobejana.

"It's very unfortunate," Sobejana told reporters. "In every war, there's really collateral damage. We cannot yet establish whose side had killed the girl."

Sobejana said army helicopters attacked the rebels with rockets and 19 of them were wounded. On the government side, he said two soldiers were wounded.

The largely Christian Philippines has for decades been plagued by insurgencies by Muslim rebels in its southern islands.

The government signed a peace deal with the biggest Muslim rebel group, the Moro Islamic Liberation Front (MILF), in 2014 but clashes still occur with smaller groups, such as the Bangsamoro Islamic Freedom Fighters, which broke away from the MILF in 2008.

The peace pact with the MILF has yet to be concluded and new President Rodrigo Duterte has been trying to bring together all factions to promote a broad peace in the south.