By Hader Glang 

ZAMBOANGA CITY, the Philippines

One day after 15 government soldiers were killed, two of them beheaded, by a Daesh-linked group in the southern Philippines, heavy fighting between the two have resumed.

 Army soldiers of the Philippines army's 21st Infantry Battalion are reported to again be battling a heavily-armed Abu Sayyaf unit, led by sub-leader Jamiri Jawong Jauhari, in the Abu Sayyaf stronghold of Patikul.

In a news briefing Tuesday afternoon, Western Mindanao Command spokesman Major Filemon Tan Jr. emphasized that since Aug. 26 efforts to eradicate the group have intensified, with the Abu Sayyaf suffering heavy losses of its own.

"The number of killed Abu Sayyaf bandits is already 30 while 11 others [have been] injured. On the government side, we suffered 15 killed in action and 29 others wounded," Tan told defense reporters in a press briefing at Camp Navarro, Upper Calarian, Zamboanga City.

"So the total number of deaths on both sides is 45, and 40 others including our troops and Abu Sayyaf were injured since Friday fighting."

Tan reflected on the deaths of the 15, which occurred Monday -- Philippines National Heroes Day -- in a fierce gunbattle in Patikul, less than 10 kilometers (6.2 miles) from Jolo, the capital of southern Sulu province.

"Our forces fought gallantly, the firefight was intense and our troops sacrificed their lives to give the next generation the peace and security they truly deserve," Tan said. 

"We will mourn the loss of our brothers, but it will not dampen the fighting spirit of our troops. The momentum is on our side and we will continue this fight until we accomplish the mission."

He warned that whoever blocks troops or helps the Abu Sayyaf would be dealt with severely.

"What you see is just the tip of the iceberg - more troops, more equipment and more firepower will be committed to destroy the Abu Sayyaf. It is just a matter of time," said Tan.

Meanwhile, Joint Task Force Sulu Commander Brig. Gen, Arnel de la Vega said in a statement that intense fighting has been ongoing in Sulu since 1.50 p.m. (0550GMT) Monday.

The 15 soldiers were reported to have died at 4.30 p.m. in the village of Maligay in Sulu.

"In a fierce ongoing armed encounter, two ASG [Abu Sayyaf] members were killed and a number of them severely wounded as they withdrew southeast," Lobos said.

The security forces suffered zero casualties, he added

Tan placed the total Abu Sayyaf fighters in Sulu and Tawi-Tawi at 481, but added that the military does not have exact figures on how many sympathizers, supporters or "operatives recruited through dubious means" the group has.

Since 1991, the Abu Sayyaf -- armed with mostly improvised explosive devices, mortars and automatic rifles -- has carried out bombings, kidnappings, assassinations and extortion in a self-determined fight for an independent province in the Philippines.

It is among two militant groups in the south who have pledged allegiance to Daesh, prompting fears during the stalling of a peace process between the government and the country's biggest Moro group that it could make inroads in a region torn by decades of armed conflict.