Another 16 soldiers and five militants were hurt in the clash that erupted when troops approached rebels from the Abu Sayyaf group in a jungle off Patikul town in predominantly Muslim Sulu province, said Brig. Gen. Allan Arrojado.
Among them was one-armed rebel commander Radulan Sahiron, who led the Abu Sayyaf faction, Arrojado said.
The US government has offered $1 million for any information leading to the capture and prosecution of Sahiron, one of the original Abu Sayyaf commanders who has endured years of fighting and has been blamed for several bomb attacks and kidnappings.
In a recent video posted on a Facebook account linked to the militants, they threatened to kill the hostages unless a huge ransom was paid by April 8. The Philippine military said the government's no-ransom policy remains and security forces would continue efforts to secure the safe release of the captives.
The Abu Sayyaf is one of several Muslim rebel groups in the predominantly Catholic nation's south. The main rebel group has agreed to peace in exchange for autonomy.