The Association of Southeast Asian Nations on Friday strongly condemned the bombing incident at the Mindanao State University in Marawi City on 3 December that killed at least four people and injured 50 others.
In a statement, the ASEAN foreign ministers denounced what it described as a "heinous terrorist attack."
"We fully support the efforts of the Government of the Philippines in addressing the situation and bringing the perpetrators to justice," the 10-member regional bloc said.
"We extend our deepest condolences to the bereaved families and wish the injured a speedy recovery," it added.
The ASEAN reiterated its commitment to work with the Philippines in combatting terrorism in the region.
"We stand in solidarity and are ready to work with the Government and people of the Philippines during this difficult time," it said.
"We also reaffirm our commitment to continue, strengthen, and enhance regional counterterrorism cooperation to prevent recurrence of terrorist incident in the future," it added.
Earlier, the Armed Forces of the Philippines said that one of the suspects in the bombing, identified as Jaffar Gamo Sultan, had been arrested in Barangay Duay Proper in Marawi City.
Sultan is tagged as one of the companions of a certain Omar, the person who took the improvised explosive device to the Catholic liturgy at the Dimaporo Gymnasium on 3 December.
The Islamic State militants earlier claimed responsibility for the deadly attack in Marawi, which was once occupied by the Maute group for several months in 2017.
In the message application Telegram, the group said its members had detonated the bomb.