MANILA (Reuters) - Philippine security forces killed at least 15 al Qaeda-linked Islamist militants in an attempt on Wednesday to rescue foreign captives on a remote southern island, an army general said as Manila redoubled an offensive against Muslim rebels.
There was no immediate word on the fate of 10 foreign and Filipino hostages, including two Malaysians and a Dutch national, believed to be in the custody of Abu Sayyaf militants on Jolo island.
Brigadier-General Alan Arrojado, commander of military units on Jolo island, said they fired several howitzer rounds as U.S.-trained army commandos battled about 100 Abu Sayyaf militants near another rebel stronghold in the town of Indanan.
"We killed 15 rebels and wounded an undetermined number as they withdrew deep into the jungles," Arrojado told journalists by phone from his base. "We are pursuing them, we have sent in more reinforcements." No army casualties were reported.
The small but violent Abu Sayyaf has been blamed for bomb attacks in the south, kidnappings-for-ransom and beheading of captives, including an American citizen in 2001. The rebels are led by Yasser Igasan, seen as having close links to al Qaeda.
Philippine armed forces launched an assault on Abu Sayyaf after Manila ordered an all-out offensive to prevent possible copycat attacks after a bombing at a shrine in the Thai capital Bangkok on Monday that killed at least 20 people.
"I have directed our forces to be extra vigilant and conduct measures to prevent similar incidents occurring in our country," said General Hernando Iriberri, the Philippines military chief, raising security alert nationwide at the highest level.
Iriberri ordered pre-emptive strikes to disrupt what he called plans by Islamist militants to carry out bombings in important urban centers on Mindanao, a major southern island in the Southeast Asian archipelago nation of 100 million people.
Since 2002, a small U.S. military contingent has been training and advising Philippine forces in fighting Abu Sayyaf and two other militant factions -- the Bangsamoro Islamic Freedom Fighters and a small group claiming affiliation with the ultra-radical Islamic State movement.
(Reporting By Manuel Mogato; Editing By xxxxx)