Fifteen soldiers were killed and 10 wounded in a 90-minute battle with the Abu Sayyaf in Patikul town, Sulu province on Monday after the military reported success against the armed group last week, a military spokesman said Tuesday.

Monday’s encounter was the second in three skirmishes against the Abu Sayyaf, and the most deadly to the Philippine military as the country marked National Heroes Day.

In a statement, Presidential Spokesperson Ernesto Abella said as the national defense department announced on August 29, it is “adding five battalions or about 2,500 soldiers for the anti-ASG (Abu Sayyaf Group) offensive.”

“These troops will only be assigned in Sulu with a mission of destroying the ASG and rescuing its hostages,” said Abella.

Col. Edgard Arevalo, Armed Forces of the Philippines public affairs office chief, said most fatalities were from the 35th IB and 21st IB which encountered around 120 Abu Sayyaf members in the vicinity of Sitio Kan Jalul, Brgy. Maligay also of Patikul, Sulu around 4:30 pm.

An Army battalion clashed with approximately 30 Abu Sayyaf members at Sitio Kugan, Barangay Bakung, Patikul town at 1:50 pm, killing two of the attackers, Arevalo said.

In the second battle, which was around 3:42 pm troops of 4th Scout Ranger Battalion encountered more or less 80 Abu Sayyaf members in the vicinity of Brgy Kuttong, Talipao town.

After sustaining four casualties during the 30-minute firefight, the gunmen withdrew westward. Two soldiers were wounded.

Flags in all military camps were put on half-mast Tuesday. General Ricardo Visaya, chief of staff of the Philippine military, said the armed forces will continue with its mission to eliminate the Abu Sayyaf

"There may still be casualties along the way as we advance this solemn duty to eradicate these bandits and terrorists of 25 years, but we will not stop until we rid our country of the menace this ASG brings to the world," Visaya said.

Arevalo said Visaya ordered soldiers to “keep the pressure on the enemy until they wear out. Just ensure they won't be able to leave the island and we will be triumphant in the end.”

Visaya said more troops will be sent to destroy the Abu Sayyaf. “It is just a matter of time. We appeal to every Filipino to pray for our troops,”

The military operations have been going on against the Abu Sayyaf since Friday, Aug. 26, a day after the bandits beheaded an 18-year-old male. Robina Asido-Celerina Monte/DMS