Authorities in the Philippines say they think Islamic separatists carried out a bombing that killed 21 people at an airport on Tuesday. At least nine people have been arrested in connection with the attack. Philippine President Gloria Arroyo pledges to punish those responsible for the blast.
Authorities say among those detained are several members of the largest Islamic separatist group in the Philippines, the Moro Islamic Liberation Front.
The MILF, however, denies any role in the bombing at the Davao City Airport on Tuesday, the worst terrorist incident in the Philippines in three years, with more than 150 people injured.
A much smaller separatist group, the Abu Sayyaf, reportedly has claimed responsibility for the attack. However, senior Philippine police officials doubt the claim, saying they think the much larger MILF is responsible.
Visiting the site of the bombing on Wednesday, Philippine President Gloria Arroyo vowed to apprehend those who carried out the attack.
Roberto Copco, President Arroyo's deputy chief of staff, says the army is hunting the bombers.
"We have enough troops to go after these people," he said. "What we need is good information and good intelligence so that we can hunt down and finally crush these terrorist groups."
The southern Philippines has been hit by several bombings in the past few weeks, most blamed on separatist rebels. Earlier attacks caused few casualties, but some knocked out power to all of Mindinao province for several hours last week. At least two other bombings have been reported since the Davao airport blast - the latest was at midday Wednesday. So far, no injuries have been reported.
Mr. Copco says the government is acting to prevent new attacks, especially in Davao.
"We are now intensifying security at all public places in the Philippines…. While Davao is a big city in Mindinao, we are confident that security there has been tightened and that the public there will be safe," he said.
Last month President Arroyo called for the military to crush the Abu Sayyaf militants in three months. The group, which the United States considers a terrorist organization, claims to be fighting for an Islamic state in the southern Philippines. It is best known, however, for a series of kidnappings and murders.
Analysts in the Philippines say Tuesday's bombing could signal an upsurge in violence and even the beginnings of an alliance between Islamic separatists and Communist guerrillas - who also are active in the southern Philippines.