ZAMBOANGA CITY, Philippines - A military offensive in Sulu against the Abu Sayyaf continued Tuesday after the bandit group beheaded one Canadian captive in the hinterlands of Patikul town.

At least 13 Abu Sayyaf members have been killed since Sunday, when the military mounted the offensive to keep the bandit group from making good on a threat to harm its captives.

Maj. Filemon Tan Jr., spokesman of the military's Western Mindanao Command, said the operation had been ongoing even before the Abu Sayyaf executed Canadian John Ridsdel.

Tan said the troops even clashed with the Abu Sayyaf outside Patikul on Sunday and inflicted casualties on the group. He said troops on the ground reported around 10 Abu Sayyaf militants among the 13 reported fatalities.

“Our forces continue to press the assault on the ground,” Tan said.

He said the troops were provided air support by the Air Force's 3rd Air Division based in Zamboanga City.

At least four MG-520 attack helicopters and two UH-1 "Huey" helicopters could be seen over areas of Patikul town, where troops are closing in against the Abu Sayyaf group.

The Naval Forces Western Mindanao also placed its two attack helicopters on standby in Jolo, the capital town of Sulu province.

The military has taken the safety of hostages still being held by the Abu Sayyaf group into consideration in its operation, Tan said.

“The AFP and the PNP calculate [their] movements. The safety of the kidnap victims is of primary concern as plans were carefully made before they (the plans) are executed on the ground,” Tan said.

Meanwhile, the Armed Forces of the Philippines and the police condemned the gruesome execution of Ridsdel. “The AFP and the PNP condole with the Canadian government and the family of John Ridsdel who died in the hands of the ASG (Abu Sayyaf group),” Tan said.

He said operations against the Abu Sayyaf will continue.