The Philippine government refuses to negotiate with Muslim rebels who are threatening to kill their American hostages. Officials continue to call for the unconditional release of the hostages, who have been held for nearly year.

Senator Rudolfo Biazon, vice chairman for the committee on defense, has said there will be all out war if the Abu Sayyaf carries out its threat to kill the hostages.

Senator Biazon has said if the Muslim rebels kill the hostages, the government should make full use of its resources to destroy what he described as a bandit group.

National security adviser Roilo Golez Thursday echoed repeated the government's position of not negotiating with the rebels.

Abu Sabbaya, a spokesman for the Abu Sayyaf told the administration to "start looking for dead bodies." He said the rebels are no longer interested in making another offer for talks.

In an interview with Radio Mindanao, Abu Sabbaya said if he sees the fight favors the Philippine military, he will kill Martin and Gracia Burnham. The two missionaries from the United States were kidnapped from a resort last year.

Last year, the group beheaded another kidnap victim, American Guillermo Sobero.

About 1,000 U.S. soldiers are participating in an anti-terrorism exercise with Philippine troops. The exercise is aimed at the crushing the Abu Sayyaf, which claims to be fighting for a Muslim state in the southern Philippines.

Also Thursday, Philippine police said they have arrested suspects in a grenade attack that killed several people. The attack Wednesday in the southern town of Notre Dame injured more than 120 people attending a local festival.

Police have not identified the suspects, but said the explosion may have been revenge for a dispute about performing at the festival.

Earlier, however, a regional military commander said Muslim separatists might have set off the explosion. A recent series of bombings in the southern Philippines has been blamed on rebels.