Philippine officials say at least 17 people have been injured in a bomb explosion they believe was either an extortion attempt or retaliation for battle losses by Muslim militants in the south.

Regional army commander Maj. Gen. Cirilito Sobejana says the bomb went off Wednesday outside a restaurant in Isulan town. He says unidentified people had previously tried to extort money from the restaurant owner, who refused to pay up. The attack may also have been carried out by Muslim militants belonging to the Bangsamoro Freedom Fighters who have been targeted by military offensives.

Isulan in Sultan Kudarat province has been hit by bombings by suspected Muslim militants despite tightened security in a region where the government and the largest Muslim rebel group are implementing a new autonomy deal.