The unprecedented surge in air strikes carried out by Syrian forces this week is a desperate attempt by President Bashar Assad's regime to reverse recent gains by rebel fighters, analysts and rebels say.

The air raids, they say, are not so much aimed at hitting rebel positions but at striking enough fear and provoking enough anger to turn local populations against the opposition fighters in their midst.

Three years after he promised a rapt Cairo audience a shift in his country's unpopular Middle East policy, U.S. President Barack Obama goes to the polls leaving disappointment in a region swept by the Arab Spring.

Obama's critics say he has not honored his pledges, such as settling the Palestinian-Israeli conflict, or improving relations with Muslim countries.

China said Thursday it had made "constructive new suggestions" to end the bloodshed in Syria, including a phased region-by-region ceasefire and the formation of a transitional government.

In an apparent attempt to position China at the heart of efforts to solve the issue, the foreign ministry gave a detailed account of proposals it made to Lakhdar Brahimi, the visiting United Nations-Arab League joint peace envoy.

A Kuwaiti court on Thursday ordered the release on bail of opposition leader Mussallam al-Barrak following a night of violent protests that left dozens hurt, his lawyer said.

News of the court order came as opposition groups convened in an emergency meeting in the wake of the night-long clashes, which also saw more than 20 demonstrators arrested, according to activists.

The head of the main opposition Syrian National Council on Thursday blamed the international community's failure to react to the country's conflict for fueling Islamic extremist sentiment.

The comments came a day after U.S. Secretary of State Hillary Clinton said the opposition should "strongly resist the efforts by the extremists to hijack the Syrian revolution".

Israel has for the first time admitted assassinating the PLO's former number two, Abu Jihad, in a raid on the movement's Tunis headquarters in 1988, a newspaper reported on Thursday.

The report, published in Israel's top-selling Yediot Aharonot, said the operation was planned by the Mossad spy agency and carried out by the Sayeret Matkal commando unit.

Israeli security forces destroyed makeshift structures in a wildcat settlement outpost on Thursday, sparking protests which saw six Jewish settlers arrested, police and the army said.

"The army went to demolish two structures erected without permission near Yitzhar (settlement) and six people who demonstrated against it were arrested," police spokesman Micky Rosenfeld said.

Syrian rebels killed 28 soldiers in attacks on three army checkpoints on the main road from Damascus to the embattled city of Aleppo Thursday, a watchdog said, as a warplane bombed the outskirts of the rebel-held town of Harasta, east of Damascus.

Five rebels were also killed in the attacks near the city of Saraqeb in Syria's northwest, the Britain-based Syrian Observatory for Human Rights said.

A fuel truck exploded after hitting portions of a bridge Thursday in the Saudi capital, Riyadh, engulfing buildings and cars in flames and killing at least 22 people and injuring more than 110, witnesses and officials said.

The death toll was a significant increase in the number of reported casualties than in the first hours after the 7 a.m. explosion near the Saudi National Guard building in an industrial area in the city's eastern district. Columns of smoke could be seen rising from scene.

French President Francois Hollande on Wednesday urged Israel and the Palestinians to resume peace talks without any conditions, while criticizing continued Israeli occupation.

"Only negotiations can lead to a definitive solution," he said after his first direct meeting with Israeli Prime Minister Benjamin Netanyahu in Paris.