Heavy fighting between the Syrian army and Islamist rebels erupted on Monday on the Golan Heights, where the militants have wrested control of a key frontier crossing which had been operated by the United Nations.
It was not clear whether the forces loyal to Syrian President Bashar al-Assad had managed to retake control of the Quneitra crossing from the rebels of the al Qaeda-linked Nusra Front.
Persistent gunshots and explosions from mortar shells and other munitions could be heard on the Israeli-controlled side of the frontier and combatants could be clearly seen targeting each other with their weapons.
At least one tank belonging to the Syrian army was also involved and some rebels could be seen a few meters (yards) away from the frontier fence.
A large Syrian flag that had been flying for days between the Quneitra crossing and the abandoned town was taken down and a United Nations position in the area, thought to be unmanned, was pounded with mortar shells.
The Syrian Observatory for Human Rights, which monitors violence in the Syrian civil war, said the Nusra Front and allied fighters were battling government forces near the Quneitra crossing and in the nearby village of al-Hmaydieh.
The Observatory, which says it gathers information from all sides in the conflict, said there were confirmed casualties on both sides.
Speaking to Reuters, Observatory founder Rami Abdelrahman said the Nusra Front's aim appeared to be "to end once and for all the regime's presence in the area and it also appears that the goal is to expel the international observers".
On Sunday, Israel's military said it had shot down a drone that flew from Syria into Israeli-controlled airspace over the Golan.
It was not immediately clear who had dispatched the unmanned aircraft or the nature of its mission in an area where fighting from Syria's civil war has occasionally spilled over into Israeli-held territory.
In a statement, the military said the drone was downed by a Patriot missile near the Quneitra crossing between the Israeli-held Golan Heights and Syria.
A contingent of 44 UN peacekeepers from Fiji was detained on the Syrian side of the Golan by Islamist militants on Thursday. The head of the Fijian army said on Sunday negotiations for their release were underway.
More than 70 Philippine troops trapped by Islamists in a different area on the Syrian side of the frontier have been moved to safety, the United Nations and authorities in Manila said.
Israel captured the Golan Heights in the 1967 Middle East war and beefed up defenses in the area after the outbreak of the Syrian civil war more than three years ago.
A UN peacekeeping force has monitored the disengagement zone on the plateau between Israel and Syria since 1974, following the 1973 Arab-Israeli war.
Pro-government activist arrested
On another note, Syrian authorities have arrested a pro-government activist who launched a social media campaign calling on officials to provide information about hundreds of missing soldiers, residents and activists said on Monday.
The arrest on Friday has fueled an already unusually bold push by some government supporters to hold officials accountable for the rising death toll among President Bashar al-Assad's loyalists.
Before his disappearance, activist and lawyer Mudar Hassan Khadur represented a rare but growing voice of public dissent among Alawites, an offshoot sect of Shi'ite Islam to which Assad and many of his top military and security advisors belong.
Khadur's detention has further outraged many in the community, which has typically been more shy about public dissent even as the three-year-old conflict has left few Alawite families untouched by death.
Restrictions on the information flow from Syria make it difficult to gauge how widespread such sentiments are.
A post on Khadur's Facebook page at the weekend said he had been arrested in Damascus after authorities had contacted him and promised to help investigate the fate of soldiers missing from an airbase seized by Islamic State militants last week.
In a rare display of shaming officials, the post, which was shared over 156 times, named two senior military officers as personally responsible for Khadur's safety. Another post called on Assad to intervene.
"Mudar Khadur. Not a traitor. Not a collaborator. Not a terrorist," said the post, referencing accusations that the Syrian government and its staunch loyalists typically use to describe rebels and dissidents.
"We must all stand with Mudar."
Reuters attempted to contact Khadur over the Internet before his arrest, but received no response. There was no mention on Syrian state media of Khadur's arrest.
Khadur's campaign began after last week's fall of Tabqa airbase, the last major position held by government forces in the northern Raqqa province, which is largely controlled by Islamic State, a hardline al Qaeda offshoot.
Islamic State militants later posted footage online appearing to show their fighters executing scores of captives wearing nothing but their underwear. They claimed to have killed 250 soldiers. The Syrian Observatory for Human Rights, which gathers information from all sides in the conflict, said at least 120 have been confirmed dead.
Yet government-run Syrian media barely reported the defeat, calling it a tactical withdrawal, and avoided any mention of the fallen soldiers, which left many in the Alawite community particularly incensed.
Khadur may have provoked the authorities last month when he launched a Facebook page called Eagles of Taqba Military Airport shortly after the base's fall. The page has so far received more than 12,000 likes.
After Islamic State footage of the executions surfaced, Khadur and a few other government loyalists, including the president's cousin Douraid al-Assad, called for top officials including the defense and information ministers to resign.
Trending hashtags in Arabic included #MinisterofDeath, #FallenMedia, and #WhereAreThey - the last one a reference to a classic Arabic song that became symbolic of disappearances during the 1975-90 civil war in neighboring Lebanon.
REUTERS