Austria's government says it is withdrawing its UN peacekeeping contingent from the Golan Heights because of the escalation of fighting in the area.
The announcement in Vienna by Chancellor Werner Faymann came after Syrian rebels briefly overran an Austrian-manned crossing along the cease-fire line in the Golan.
Rebels were later repelled from the Quneitra crossing by tanks and troops loyal to Syrian President Bashar al-Assad.
The Austrian peacekeepers withdrew without being hurt.
Austrians account for about 380 of the 1,000-strong UN Disengagement Observer Force monitoring a cease-fire between Syria and Israel.
It was not immediately clear when the withdrawal would begin.
Most of the Golan plateau was seized by Israel from Syria in the 1967 Six-Day War.
Quneitra is the only direct passage in the Golan between Israel and Syria.
Meanwhile, the United States has demanded that Lebanese Shi’ite Hizballah and Iran "immediately withdraw their fighters from Syria."
In a written statement, the White House also condemned "in the strongest possible terms" the assault on rebel forces in the Syrian border town of Qusayr, saying the fighting had "killed untold numbers of civilians and is causing tremendous humanitarian suffering."
The statement said it was clear the Syrian government could not have ousted rebel fighters from Qusayr on its own and had relied on Hizballah and Iran to complete the job.
Earlier, the Arab League also condemned the military intervention in Syria by Hizballah.
The Syrian regime on June 5 announced it had seized Qusayr after weeks of fighting.
Syrian rebels had relied on the town to bring in supplies and fighters from Lebanon.
In another development, Secretary of State John Kerry says the United States has asked France to share evidence of its assertion that Syria's government used chemical weapons against rebel forces.
France said earlier this week that its analysis of materials showed "no doubt" that President Bashar al-Assad's regime was involved in at least one attack using sarin gas.
Kerry said Washington has asked Paris for information showing precisely where the sarin had come from.
President Barack Obama has previously warned that the Syrian government’s use of chemical weapons would be a “red line” that would trigger a more forceful response from the U.S. to the Syrian conflict.
Kerry, speaking during a visit to Guatemala, said Obama’s red line "is real" and that the administration is continuing to consider all options.
With reporting by AP, AFP, Reuters, and dpa