Heavy fighting between government forces and Abu Sayyaf militants in the southern Philippines has left at least 15 rebels and three soldiers dead, officials said.

Maj. Filemon Tan, a regional military spokesman, said the clashes began early this week as troops advanced toward an Abu Sayyaf camp in Basilan Island's Al-Barka township. He said the fighting intensified on Tuesday and sporadic skirmishes were continuing Wednesday, ABC News reported on Wednesday.

At least seven militants and 13 soldiers also were wounded, with most of the government casualties hit by Abu Sayyaf snipers, he added.

The Philippines and the United States have listed the Abu Sayyaf as a terrorist organization for kidnappings, beheadings, extortion and bomb attacks. The al-Qaida-linked militants have been weakened but have survived more than a decade of US-backed offensives.

Sources: MENA