Soldiers seized explosives and bomb-making materials after heavy fighting with the militants linked to Al-Qaeda on Basilan island. One soldier was killed and dozens wounded on both sides, said Brig.-Gen. Eugene Clemen.
"Our troops found the Abu Sayyaf's bomb factory," Clemen told reporters, adding the rebels planned to disrupt the presidential and congressional elections on May 10.
Muslim separatists and Maoist guerrillas have in the past attacked voting centers and harassed people trying to vote in the country's troubled south.
Bomb-making manuals in Arabic, mobile phones, two-way radio sets, electric circuits, switches and detonating cords were also seized from the militants' base in a wooded area near Sumisip town, Clemen said.
On April 13, Abu Sayyaf militants, dressed in army and police uniforms, detonated two crude bombs on Basilan's main city and exchanged gunfire with troops, killing 15 people and wounding more than a dozen others.
US-trained troops had scored tactical successes against the Abu Sayyaf when they killed a senior militant leader, Albader Parad, in a gunbattle in February.
But experts say it remained a potent security threat.
