UNITED NATIONS -- The U.N. peacekeeping chief said Friday there is a possibility of a cease-fire that would allow the release of 21 peacekeepers being held captive by Syrian rebels.

Herve Ladsous told reporters after briefing the Security Council that the peacekeepers, all Filipinos, are being held in the basements of four or five houses in the village of Jamlah, just a kilometer (less than a mile) from the Israeli-controlled Golan Heights.

The peacekeepers are apparently safe, he said, but the village "is subjected to intense shelling by the Syrian armed forces."

Ladsous said U.N. officials in the region and at headquarters have been working 24/7 to gain their freedom.

"As of now, there is perhaps a hope -- but I have to be extremely cautious because it is not done yet -- but there is the possibility that a cease-fire of a few hours can intervene which would allow for our people to be released," he said.

"If that were to happen, as we all hope," Ladsous said, "we would strongly expect that there not be retaliatory action by the Syrian armed forces over the village and its civilian population after our people have left."

Syria's U.N. Ambassador Bashar Ja'afari denied that government forces were shelling the village of Jamlah, but he said they were involved in military activity in the suburbs. He stressed that the government's goal is to see the peacekeepers released safely and said Syrian soldiers would risk their lives to see this happen.

The U.N. peacekeepers' four-vehicle convoy was intercepted Wednesday by rebels from a group calling itself the Martyrs of the Yarmouk Brigades. The convoy was stopped on the outskirts of Jamlah.

Rebels said 10 people have died in regime shelling of Jamlah and nearby villages in recent days. Fighting continued Thursday, according to activists.

The abduction of the Filipino troops -- soft targets in Syria's two-year-old civil war -- illustrated the sudden vulnerability of a U.N. force that had patrolled a cease-fire line between Israel and Syria without incident for nearly four decades. It also sent a worrisome signal to Israel about the lawlessness it fears along the shared frontier if Syrian President Bashar Assad is ousted.

The capture came a week after the announcement that a member of the peacekeeping force is missing.

Ladsous said that in light of the volatile situation in the area, the United Nations has vacated two positions which were particularly exposed to gunfire, one at the extreme south of area of separation.

"In a wider sense, of course we are looking very closely at the 'modus operendi' of the mission in the situation it is facing, of a very degraded safety and security conditions," he said.

The U.N. monitoring mission, known as UNDOF, was set up in 1974, seven years after Israel captured the Golan and a year after it managed to push back Syrian troops trying to recapture the territory in another regional war.

For nearly four decades, the U.N. monitors helped enforce a stable truce between Israel and Syria.

But in recent months, Syrian mortars overshooting their target have repeatedly hit the Israeli-controlled Golan. In Israel's most direct involvement so far, Israeli warplanes struck inside Syria in January, according to U.S. officials who said the target was a convoy carrying anti-aircraft weapons bound for Hezbollah, a Lebanese militia allied with Assad and Iran.