The Philippines on Thursday demanded the immediate and unconditional release of 21 of its nationals working as UN observers who have been kidnapped by Syrian rebels.
According to reports, the group is currently being held by armed opposition fighters near the Golan Heights, an increasingly volatile zone separating Israel and Syria. 
The observers had reportedly been monitoring the ceasefire line between Syria and Israel, which captured the Heights in 1967.
The UN says the peacekeepers were on "a regular supply mission" on Wednesday when they were stopped near an observation post by the armed men.
On Thursday, a statement from the foreign ministry said: "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."
"The apprehension and illegal detention of the Filipino peacekeepers are gross violations of international law," it said.
A video posted online and circulated by the UK-based Syrian Observatory for Human Rights (SOHR) on Thursday showed men claiming to be Syrian rebels standing next to vehicles marked with the letters "UN".
The men identify themselves as the "Martyrs of Yarmouk" and are heard saying that the UN personnel would not be released until forces loyal to Syrian President Bashar al-Assad withdrew from the village of Jamla in the area.
Colonel Arnulfo Burgos, spokesperson of the Armed Forces of the Philippines, told Al Jazeera that the abducted peacekeepers are "safe" and being "treated as guests" by the Syrian fighters.