Updated

Officials say heavy fighting between government forces and Abu Sayyaf militants in the southern Philippines has left three soldiers and 15 rebels dead.

Military spokesman Maj. Filemon Tan said the clashes began early this week as troops advanced toward an Abu Sayyaf mountain camp in Basilan Island's Al-Barka township. He said the fighting intensified Tuesday and sporadic skirmishes were continuing Wednesday.

He said 13 soldiers and seven militants were also wounded.

Tan said troops were advancing slowly because of sniper fire and had not yet captured the camp.

The Philippines and the United States list the Abu Sayyaf as a terrorist organization for kidnappings, beheadings, extortion and bomb attacks.