ZAMBOANGA CITY, 29 March 2006 — Police yesterday said they were looking into the possibility that an extortion gang was behind Monday’s bomb attack that killed nine people in a grocery store in the southern Philippine island of Jolo.

Supt. Ahirun Ajirim, the chief of police in Sulu province, said an extortion letter was found at a nearby drugstore shortly before a bomb ripped through a two-story building of the Sulu Consumer’s Cooperative Store in downtown Jolo at 1:15 p.m.

Twenty other victims, mostly Muslims, were around 1.15 p.m. and that most of the victims were Muslims.

The explosion was so powerful that it totally destroyed the facade of the building and debris thrown across the street. The scene reminded locals of the television footages on the aftermath of suicide bombings in Iraq.

President Gloria Macapagal Arroyo told investigators to “leave no stone unturned in the hunt for the perpetrators and I ask our people to remain calm and vigilant.”

“Indeed, terror never sleeps,” Arroyo said in a statement in the national capital, Manila. She renewed her call for Congress to pass an anti-terrorism law.

Ajirim said he suspected that Al-Qaeda-linked Abu Sayyaf rebels were involved in the bombing. He said the letter, addressed to the cooperative, included two mobile phone numbers, apparently to be used to contact the extortionists, and authorities would try to track them down.

“It appears they were asking for some money, but (the letter) did not mention any amount,” he told The Associated Press by telephone. It was not immediately clear whether there were any previous letters.

“We will give an example to those who do not cooperate. Listen, there will be an explosion at the co-op now,” the letter said.

An armed man who was arrested shortly after Monday’s blast was released because he turned out to be a Philippine marine, Ajirim said.

The victims were store personnel and shoppers. The store had just reopened after a lunch break and was not yet crowded when the explosion occurred, social worker Maydelyn Bahjin said.

Brig. Gen. Alexander Aleo, the military commander in the troubled island, earlier also said the blast had the handiwork of the Abu Sayyaf group, blamed for the series of bombings and kidnappings in the south.

Jolo, the biggest of a cluster of islands in the province of Sulu, is a stronghold of the Abu Sayyaf, notorious for kidnappings and terror attacks. It was also the venue of a counterterrorism exercise last month between Philippine and US troops.

“We are still investigating who were behind the blast, but the attack had the trademark of the Abu Sayyaf,” Aleo said.

A small group of heavily US military advisers stationed in Jolo were helping Filipino soldiers investigate the bombings.

“We deplore the targeting and killing of innocent civilians. With the Armed Forces of the Philippines, we are committed to continue to provide humanitarian assistance to the people of the Sulu region,” said Col. James Linder, commander of the Joint Special Operations Task Force in the Philippines.

Just two weeks ago, local troops captured alleged Abu Sayyaf weapons courier Julkaram Hadjail on Jolo and security forces killed several militants in a separate clash on the island. Security forces also recovered early this month a cache of explosives and homemade bombs near a highway in Jolo’s Indanan town where troops regularly pass.

Officials said the cache included plastic containers filled with ammonium nitrates and TNT and all rigged to electronic timers and cellular phones to trigger detonation when scavengers discovered them near a garbage dump along a road in the village of Tagbak . The highway links the towns of Indanan, Maimbung and Talipao which the military regularly uses to transport troops.

Last month, one civilian was killed and more than two dozen people were wounded when a powerful bomb exploded outside a military base in Jolo island.

The blast destroyed a karaoke bar just several meters away from the base frequented by soldiers. The Abu Sayyaf also fired two rounds of rifle grenade near a military post in Jolo’s Mount Karawan and killed a police officer and beheaded a civilian in downtown area. (With a report from AP)