Rebels have refused to free 21 Filipino UN peacekeepers held hostage in the Golan Heights until Syrian troops pull back from the ceasefire zone.

The 21 Filipino soldiers, in the region as part of the UN Disengagement Force, which has been monitoring a ceasefire between Syria and Israel, were held for a second day on Thursday.

The rebels want Syrian troops to move 20 kilometers (12 miles) back from Jamla before any release of the hostages, according to AFP.

The Philippines’ Department of Foreign Affairs said they were intensifying negotiations with the rebels.

“The demand of the rebels for the repositioning of Syrian forces in the area of Jamla is still outstanding so this is still being worked out,” Foreign Secretary spokesman Albert Del Rosario said.

Diplomats scrambled to secure the immediate release of the Filipino troops, as concern mounted that their seizure might force more governments to withdraw their contingents from the already depleted UN mission.

The Philippine government “strongly condemned” the detention of the peacekeepers which Del Rosario said was a “gross violation of international law”.