ZAMBOANGA CITY, 30 March 2006 — A homemade bomb exploded inside a passenger bus in the southern Philippine city of Digos yesterday, wounding as many as 7 people, the police and military said.

The blast occurred shortly before noon as the bus, owned by Weena Transit, was returning to its city depot from nearby Davao City. Several buses were also damaged by the explosion.

Passengers and some vendors at the terminal were injured in the bus attack, said Ninang Hadjaril, police superintendent of Davao del Sur province.

It was not immediately how many passengers were in the bus when the explosion occurred.

“There is an investigation going on and we still don’t know who were behind the latest explosion,” said Maj. Gamal Hayudini, spokesman of the military’s Southern Command based here in Zamboanga City.

No group has claimed responsibility for the attack, the first after a lull for so many months. Bus bombings are a common fare in Mindanao, where communist rebels and Moro separatist fighters, extremists and kidnap-for-ransom gangs abound.

Investigators say the communist New People’s Army (NPA) and Abu Sayyaf extremists were among the immediate suspects. A military report said the bomb was probably made from ammonium nitrate, a banned fertilizer commonly used by insurgents to make homemade explosives.

Communist insurgents are actively operating in Davao del Sur province, of which Digos is the capital. Davao del Sur is on the southeastern part of Mindanao, the largest island in the southern Philippines.

Authorities had previously linked communist guerrillas to extortion activities on bus operators in the province.

“We are investigating if the NPA is behind this since it’s their anniversary,” provincial police officer Reggiette Tecson said, referring to the 37th founding anniversary of one of Asia’s longest-running communist insurgencies.

In the western part of Mindanao, a man claiming to be a spokesman of the Al-Qaeda-linked Abu Sayyaf group warned of terror attacks in Zamboanga City and nearby Basilan island, a local radio network reported.

“The next bombings will be in Zamboanga City and Basilan,” said a cell phone text message sent by self-proclaimed spokesman Abu Omar to the RGMA network.

The warning came just two days after a powerful Abu Sayyaf bomb explosion ripped through a two-story convenience store in Jolo Island, killing 9 people and wounding more than two dozens. Security officials appealed to the public to stay calm and be vigilant, saying, authorities were hunting down members of the Abu Sayyaf, blamed for the series of terrorism and kidnappings.

for ransom in the southern region.

“We urge the public to cooperate with authorities and report to us any suspicious persons or abandoned package. Do not listen to rumors, but stay vigilant,” said military spokesman Major Hayudini.

He said Omar had been sending threat letters in the past to different radio and television stations in Zamboanga, but his real identity remains unknown. Omar also previously threatened to kidnap and kill local journalists who criticized the Abu Sayyaf.

It was not immediately known if Omar also claimed responsibility for the attack, but the Southern Command has linked Abu Sayyaf militant Ismin Sahiron to the bombing in Jolo.

Sahiron is the son of Radulan Sahiron, a senior Abu Sayyaf leader in Jolo and wanted by the United States for terrorism.

The US Department of Treasury has included in its blacklist the elder Sahiron and two other Abu Sayyaf leaders Jainal Antel Sali Jr. and Isnilon Totoni Hapilon.

The Abu Sayyaf had been implicated by authorities in previous bombings of three passenger buses during last year’s Valentine Day celebration in the southern port cities of General Santos and Davao, and Manila’s suburb of Makati, the country’s financial district.

At least 7 people were killed and dozens injured in the three attacks owned up by a senior Abu Sayyaf leader, Abu Solaiman.

The group was also implicated in the December 2004 bombing of General Santos, where more than a dozen people were killed, and similar attacks in Zamboanga City and Cotabato provinces.