Philippines(AFP) - The military combed a southern Philippine island today to track down Abu Sayyaf Muslim guerrillas fleeing with up to 59 hostages, including three Americans, following a failed rescue attempt.

"We are are doing our best to track them down and at any time now there should be contact," military spokesman Brigadier General Edilberto Adan told a news conference.

He said there was a virtual naval blockade to contain them on the southern Basilan island but expressed concern that other rebel groups fighting the government could offer them boats to flee or provide sanctuary.

National Security Adviser Roilo Golez said the Abu Sayyaf gunmen might have taken with them up to 50 hostages from about 200 people they held captive while in a hospital and church they had occupied in Lamitan town in Basilan.

This is in addition to nine hostages, including three Americans, they took from a tourist resort off the western island of Palawan on May 27.

The Abu Sayaf rebels first took 20 hostages from the resort but nine of the captives fled while the rebels were battling the military as they were holed up in the hospital.

Two others - staff from the resort - were slaughtered by the captors. One was beheaded.

"It is possible that they might be holding up to 50 civilians, some of them nurses," taken from the hospital before they broke through a military cordon and fled, Golez told local television network ABS-CBN television.

Based on accounts of escaped hostages, the tourist-captives still in the custody of the Abu Sayyaf rebels were in good health but shaken by the eight-day trauma, military spokesman Adan said.

A priest said he saw the three American hostages while he was held captive in the church and that they had asked him to pray for their safety.

"I saw fear in their faces," said Roman Catholic priest Rene Enriquez, who was held with American missionary couple Martin and Gracia Burnham and Californian Guillermo Sobrero inside the church.

Enriquez, who managed to escape, told the Philippine Daily Inquirer newspaper that Gracia Burnham approached him as the gunfight raged and in a shaking voice asked:"Are you a priest? Can you pray for us so we will be saved?".

"I will pray," Enriquez answered. "Her voice was shaking." The Burnham couple, long-time Philippine residents originally from Kansas, were near tears.

Sobrero, of Peruvian descent, was hugging another hostage and the priest said he gave him a softdrink.

Military spokesman Adan said about 100 guerrillas were holding the hostages and could be attempting to flee Basilan or gain sanctuary in one of the rebel-infested areas on the island.

He appealed to another rebel group, the Moro Islamic Liberation Front (MILF) which has several strongholds on the island, not to help the Abu Sayyaf guerrillas.

The MILF units had previously provided sanctuary to Abu Sayyaf members. Both the groups claim to be fighting for a separate Islamic state in the southern third of the Philippine archipelago.

Defense Secretary Angelo Reyes said yesterday that the military knew the location of the rebels but would not reveal it for tactical reasons.

Asked to comment on how the rebels were able to penetrate the military cordon, Golez said the soldiers had to act with restraint because the gunmen were using hostages as shields as they fled.

"The problem with the rescue and assault is that the bandits were using warm-bodied human beings as shields. So our military and police forces are restrained and that is the reason they are taking in a lot of casualties also," he explained.

Twelve soldiers have been killed and 32 others injured in the military assault against the Abu Sayyaf in the hostage crisis, military oficials said.

Meanwhile, food and psychologists arrived in this southern Philippine town today as the government moved to help hundreds of evacuees who fled weekend gunbattles with Muslim gunmen holding hostages.

Rice, sardines, noodles, blankets, clothes and medicine were shipped to battle-scarred Lamitan where residents abandoned homes at the height of the fierce fighting on Saturday, Department of Social Welfare regional chief Parisya Taraji Ceso said.

A team of psychologists and psychotherapists were also on hand to help residents deal with the trauma.