Syrian rebels on Wednesday abducted 21 UN peacekeepers in the Golan Heights ceasefire zone, the United Nations said, as the frontiers of their war against President Bashar al-Assad spread further.
The UN said it is trying to negotiate the release of the soldiers, who are from the Philippines, according to diplomats. But a rebel spokesman said the troops would be held until Assad's forces pull back from a Golan village.
About 30 armed fighters stopped a UN Disengagement Force (UNDOF) convoy in the ceasefire zone, UN deputy spokesman Eduardo del Buey told reporters. UNDOF has been monitoring a ceasefire between Syria and Israel since 1974.
"The UN observers were on a regular supply mission and were stopped near Observation Post 58, which had sustained damage and was evacuated this past weekend following heavy combat in close proximity, at Al Jamlah," he added.
UN Secretary General Ban Ki-Moon said 21 peacekeepers were seized. In a statement, he called for their "immediate" release and demanded that the Syrian government and rebels respect "UNDOF's freedom of movement and security."
There has been fierce fighting recently around Jamlah village, which is held by opposition forces.
A UN Security Council statement said "armed elements of the Syrian opposition" had abducted the peacekeepers, with the council demanding an "unconditional and immediate" release.
"Negotiations are going on and the matter is mobilizing all our teams," UN peacekeeping chief Herve Ladsous told reporters after briefing the Security Council. "It is a very serious incident."
Russia's UN ambassador Vitaly Churkin, who read the Security Council statement, said the rebels have made demands directed at the Syrian government, but did not give details.
Syrian rebels are also believed to be holding an UNDOF staffer who was seized last month.
UN diplomats and the Syrian Observatory for Human Rights director Rami Abdel Rahman said the peacekeepers were from the Philippines.
Rahman released two videos in which a rebel group, the Yarmuk Martyrs Brigade, set out their demands for the release of the peacekeepers.
In one, a man identified as Abu Kaid al-Faleh, a spokesman for the brigade, said the peacekeepers would not be freed until Syrian government forces pull back from the area.
"We call on them to withdraw all their troops to their bases. If they do not withdraw, these men (UN troops) will be treated as prisoners," he said.
In a second video, the same spokesman accused UNDOF of working with the army to try to suppress the insurgency and help regime forces enter Jamlah.
"The Syrian regime, the UN and the European countries are all collaborators with Israel," he said.
The United Nations has reported a growing number of incidents in the Golan over the past year. It has sent extra armored vehicles and communications equipment to reinforce security for the mission.
Shells from the Syrian side have landed in the ceasefire zone and on Israeli territory. Syrian government tanks have entered the zone several times, according to the UN.
Up to the end of February there were about 1,000 troops from Austria, Croatia, India and the Philippines operating in the ceasefire force.
But Croatia announced last week that it is withdrawing its 100 troops from UNDOF. The Croatian government said it feared for the soldiers' safety after reports that Saudi Arabia had bought arms from Croatia and then provided them to the Syrian rebels.
Canada and Japan withdrew their small contingents in recent months because of security fears.