Manila - The Philippine armed forces on Tuesday ignored a demand by Islamic militants holding three International Committee of the Red Cross (ICRC) staff on a southern island to stop military operations to rescue the hostages.

Armed forces chief of staff General Alexander Yano said there was no halt in military operations to rescue Swiss Andreas Notter, Italian Eugenio Vagni and Filipino Mary Jean Lacaba, who were seized last week on Jolo island, 1,000 kilometres south of Manila.

The three hostages, who were abducted after visiting the provincial jail on Jolo, are being held by al-Qaeda-linked Muslim Abu Sayyaf rebels in the jungles of Indanan town.

About 1,500 troops have been dispatched to track down the guerrillas and to rescue the hostages.

"If we slacken the pressure then there will be more freedom of movement for the group," Yano said. "Pressure by the military should be maintained, sustained, so that we can contain them in an area."

The victims have been able to talk with their co-workers several times since their kidnapping and said they were unharmed and were being held together in a place.

In one of their telephone calls, the hostages said their kidnappers were demanding that the military halt the rescue operations.

The ICRC is planning to send two staff from Geneva to the Philippines to help in the negotiations, according to media reports coming out of Geneva, quoting ICRC deputy director for operations Dominik Stillhart.

Police said initial investigation showed that the three ICRC staff were seized by gunmen led by a sacked jail guard, who then turned them over to Abu Sayyaf rebels.

According to military intelligence sources, the kidnappers were led by commanders Albader Parad and Akmad Jumdail, who were planning to demand 5 million dollars in ransom for the safe release of the hostages.

The al-Qaeda-linked Muslim Abu Sayyaf rebel group has been blamed for some of the worst terrorist attacks in the Philippines.

It is also notorious for high-profile kidnapping-for-ransom cases, including the abduction of 21 European tourists and Asian workers from a Malaysian resort island in 2000. The hostages were ransomed for millions of dollars before they were freed months later. (dpa)