Syrian troops and Islamist rebels battled close to the armistice line with Israel in the Golan Heights on Monday, as the UN pressed efforts to free 44 peacekeepers held by insurgents.
The unrest on Israel's doorstep followed a spillover of mortar and gunfire into Israeli-controlled territory, putting the Jewish state on high alert and prompting it to shoot down a drone over the occupied plateau on Sunday.
Several mortar rounds fell on the edges of the ceasefire line early Monday as the combatants exchanged rocket, mortar and tank fire near the Quneitra crossing, which Al-Qaeda-linked rebels seized last week, an AFP correspondent reported.
Israel had closed off the area around the crossing after an officer was wounded by stray fire last Wednesday when insurgents led by the Al-Nusra Front took over the crossing into the Israeli-occupied sector of the Golan.
The Syrian Observatory for Human Rights, a Britain-based monitoring group, said Al-Nusra fighters were locked in fierce clashes with government troops for control of the Hamidiyeh area in Quneitra, the army's remaining stronghold there.
Al-Watan newspaper, which is close to the Syrian regime, said the army was "confronting attempts by Al-Nusra fighters and other terrorist groups" to take control of Hamidiyeh.
Meanwhile, the United Nations was working to locate and release 44 Fijian peacekeepers the insurgents captured when they overran Quneitra. Seventy-two Filipino members of the same force escaped a rebel siege on their positions nearby.
The Fijians were "safe" but their whereabouts uncertain, a military official said Saturday, indicating there was contact with the group holding them.
After a seven-hour firefight, 40 Filipino peacekeepers slipped away under cover of night after rebels rammed their Golan Heights outpost with armed trucks, the Philippine military said on Sunday.
More than 30 other Filipino troops had reached safety Saturday.
- Israel watches warily -
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Israel's Prime Minister Benjamin Netanyahu urged the international community to "stand together" with the Jewish state to face "Islamist terrorist groups that threaten our societies and our civilisation", his office quoted him as telling a visiting US senator.
Israel shot down a drone over its sector, with the army warning in a statement it would "respond to any violation of our sovereignty".
Defence Minister Moshe Yaalon toured the region on Sunday, as the army sent reinforcements along the armistice line and deployed armoured troop carriers, an AFP photographer said.
Yaalon warned that Israeli "tolerance" should not be tested.
"These past weeks we have proven that our tolerance is minimal when our integrity is struck, either intentionally or unintentionally," he said.
There has been repeated fire across the ceasefire line since the uprising in Syria erupted in March 2011, not all of it stray.
In June, Israeli warplanes attacked Syrian military headquarters and positions after an Israeli teenager was killed in what the Jewish state said was a cross-border attack by forces loyal to Syrian President Bashar al-Assad.
Israel seized 1,200 square kilometres (460 square miles) of the Golan Heights during the Six-Day War of 1967, then annexed it in 1981 in a move never recognised by the international community.
The UN peacekeepers are part of a mission that has monitored the Israel-Syria ceasefire on the strategic plateau since 1974, and Israel and Syria are technically still at war.
Peacekeepers were detained twice last year before being released safely.
The Philippines said before the latest incident that it will repatriate its 331-strong contingent for security reasons, mirroring previous moves by Australia, Croatia and Japan.
The UN Disengagement Observer Force currently has 1,200 peacekeepers from the Philippines, Fiji, India, Ireland, Nepal and the Netherlands.