Austria said on Thursday it would pull out of a UN force on the Golan Heights after battles between Syrian troops and rebels there, in a blow to a mission that has kept the Israeli-Syrian war front quiet for 40 years.

Israel, anxious for the international mission to remain in place, worried that the Golan could become a springboard for attacks on Israelis by Islamist militants fighting to oust Syrian President Bashar al-Assad.

"While appreciating Austria's longtime contribution and commitment to peacekeeping in the Middle East, we nevertheless regret this decision and hope that it will not be conducive to further escalation in the region," the Israeli Foreign Ministry said in a statement.

But the departure of the Austrians, who make up about 380 of the 1,000-member United Nations Disengagement Observer Force (UNDOF), threatens the whole operation.

"Austria has been a backbone of the mission, and their withdrawal will impact the mission's operational capacity," said UN spokeswoman Josephine Guerrero.

"The members of the Security Council expressed their deep concern at the risk that all military activities in the area of separation conducted by any actor pose to the long-held ceasefire and the local population," the UN council said in a statement.

The Security Council will meet on Friday to discuss the Austrian withdrawal. British Ambassador Mark Lyall Grant, the council president this month, said peacekeeping officials were meeting with contributing countries to see whether any states would be willing to offer troops to replace the Austrians.

"We consider UNDOF to be an extremely important mission," Lyall Grant said. "We support it and we want it to continue."

Anti-Assad rebels briefly seized the crossing between Israel and Syria, sending UN staff scurrying to their shelters before Syrian soldiers managed to push them back and reassert their control of Quneitra.

The rebel attack appeared to be an attempt to regain some momentum after Assad's forces, backed by well-trained Lebanese Hezbollah guerrillas, on Wednesday seized control of Qusair, a town on a vital supply route close to Lebanon.

In Washington, US State Department spokeswoman Jen Paski said: "We've been very clear about our concerns over regional instability caused by the crisis in Syria. This is of course another example of that, and we continue to call upon all parties to avoid any action that would jeopardize the long-held ceasefire between Israel and Syria."

(China Daily 06/08/2013 page12)