At least six people have been killed and 15 wounded in separate bomb attacks in the southern Philippines, the military and police said.

A homemade explosive device went off at a kiosk in Basilan province's Sumisip township, killing at least six and wounding 10 others at a New Year's party late on Tuesday, AP news agency reported armed forces spokesman Lieutenant Colonel Ramon Zagala as saying.

Zagala confirmed the explosion had nothing to do with firecrackers intended for New Years celebrations.

"This is really an improvised explosive device," Zagala said, adding that the motive was still unknown.

Troops and police who responded to the emergency said the party took place at the home of Manuel Casineros, a pro-government militiaman and volunteer for a nearby Catholic church.

Casineros had apparently been helping authorities protect rubber plantation workers from extortion by armed gangs like Abu Sayyaf, a group founded in the 1990s with money from Osama bin Laden, according to AFP news agency.

'Very powerful' attack

Last year, Abu Sayyaf gunmen ambushed a convoy carrying plantation workers, killing six and wounding 22 in the same area.

Police have not confirmed responsibility but suspect Abu Sayyaf was involved, said provincial police chief Senior Superintendent Mario Dapilloza said over DZBB radio in Manila, describing the blast as "very powerful".

Hours before the attack in Sumisip, a man riding a motorcycle launched a grenade at a Protestant Church in Cotabato province's Carmen township, wounding a mother, her three children and another girl, police said, adding that three men on two motorcycles were seen speeding away from the scene.

Captain Antonio Bulao, a local army spokesman, said the assailants might have planned an attack for a nearby police station, but decided to switch to a weaker target.

Al-Qaeda-linked rebel groups are known to operate in both southern provinces, according to Captain Jefferson, a local army spokesman.