Armed fighters linked to the Syrian opposition have detained about 21 UN peacekeepers in the increasingly volatile zone separating Israeli and Syrian troops on the Golan Heights. The UN Security Council and Philippine government demanded their immediate and unconditional release yesterday.

"The Philippine government is calling for the immediate release of 21 Filipino peacekeepers who are part of the United Nations Disengagement Observer Force (UNDOF) in the Golan Heights," a foreign ministry statement said.

Talks were under way for the release of the unarmed peacekeepers, who were detained on Wednesday, Raul Hernandez, Philippines foreign affairs department spokesman, said.

The foreign affairs department spokesman said that the Filipino peacekeepers were unharmed.

"The apprehension and illegal detention of the Filipino peacekeepers are gross violations of international law," the statement said.

The hostages are part of a 300-member Filipino peacekeeping unit.

Colonel Arnulfo Burgos, spokesperson of the Armed Forces of the Philippines, told Al Jazeera's Marga Ortigas that the abducted peacekeepers are "safe" and being "treated as guests" by the Syrian fighters.

The UNDOF force was established in 1974 following the 1973 Yom Kippur war to monitor the disengagement of Israeli and Syrian forces and maintain a ceasefire.

Vitaly Churkin, Russia's UN ambassador and the current Security Council president, said talks were under way between UN officials from the peacekeeping force and the captors.

Herve Ladsous, UN peacekeeping chief, who briefed the council behind closed doors, identified the captors as being from a group associated with the Syrian armed opposition, Churkin said. "There was no fighting, according to his briefing to us," Churkin said.

"My understanding is that they took over the trucks in which the UNDOF personnel was moving around."

Churkin said the capture of the peacekeepers "is particularly unacceptable and bizarre" because the UNDOF peacekeepers are unarmed and their mission has nothing to do with Syria's internal conflict.

"They are there on a completely different mission so there is no reason at all under any circumstances, any kind of sick imagination to try to harm those people," he said.

Ban Ki-moon, UN secretary-general, also condemned the capture of the peacekeepers, Eduardo del Buey, UN deputy spokesman, said.

Del Buey said the UN observers were on a regular supply mission when they were stopped by approximately 30 armed fighters near an observation post that was damaged in heavy combat last weekend and had been evacuated. — Al Jazeera