Rebels fighting the regime of President Bashar Assad on Saturday seized a key air base in the southern Syrian province of Daraa after two weeks of fierce battles with loyalist troops, a watchdog said.

"Opposition fighters loyal to al-Nusra Front, al-Yarmouk Brigade and other rebel groups seized air defense Base 38 near the town of Saida, on the road linking Damascus to Amman, in the province of Daraa," said the Syrian Observatory for Human Rights.

Police were out in force on Saturday outside the headquarters of Egypt's Muslim Brotherhood a day after more than 160 people were hurt in running street battles between Islamists and opposition protesters.

An AFP journalist reported a heavy police presence at the building in the Mokattam neighborhood, and the official MENA news agency cited a Health Ministry spokesman as saying more than 160 people were injured the night before.

U.S. President Barack Obama strolled among the ancient Jordanian ruins at Petra on Saturday, on the final leg of a four-day Middle East tour dominated by his embrace of Israel.

Obama flew by helicopter to view the rose-colored stone ruins of the ancient Nabataean city, after winds from a sandstorm abated and allowed him to make the 55-minute trip across the plains and mountains of Jordan.

The U.S. Central Intelligence Agency has been feeding information to select rebel fighters in Syria to try to make them more effective against government troops, The Wall Street Journal reported Saturday.

Citing unnamed current and former U.S. officials, the newspaper said the new CIA effort reflected a change in the administration's approach that aims to strengthen secular rebel fighters.

Syrian opposition leaders are to address an annual summit of the Arab League for the first time in Qatar on Tuesday, but the bloc's members remain divided over whether to give them Damascus's vacant seat.

The Qatari hosts are vocal champions of the rebels fighting President Bashar Assad's regime and said leaders of the armed opposition would definitely be joining Arab heads of state in Doha.

The United States has quietly unblocked almost $500 million in aid to the Palestinian Authority which had been frozen by Congress for months, a top U.S. official said Friday.

The news that the funds had finally been freed up came after U.S. President Barack Obama met top Israeli and Palestinian leaders in a landmark visit to Israel and the West Bank earlier this week.

The U.N. Security Council on Friday set aside differences on the Syria conflict to agree a rare statement condemning a suicide bomb attack on a Damascus mosque without blaming it on any side.

"The Security Council condemned in the strongest terms the terrorist attack in a mosque in Damascus," the statement said. More than 45 people, including a senior pro-government cleric, were killed in Thursday's blast.

Britain and France pressed reluctant European Union partners to supply weapons to Syria's rebels at talks Friday between the bloc's foreign ministers that appeared headed for stalemate.

As unseasonal wintry weather delayed the start of a likely showdown over the contested Franco-British push, ministers headed into Dublin's historic castle split over the consequences of lifting a nearly two-year-old embargo to tip the balance on the ground in favor of the insurgents.

President Barack Obama arrived in Jordan on Friday to face scrutiny over his Syria strategy, on the last leg of a Middle East tour after visits to Israel and the Palestinian territories.

The U.S. presidential aircraft landed in Queen Alia Airport near Amman at 1445 GMT, and he was welcomed by Foreign Minister Nasser Judeh and other top officials.

Hundreds of thousands of Syrian refugees in Jordan are stretching the kingdom's meager water resources "to the limit," two British aid agencies warned on Friday, calling for international help.

"The Syrian refugee emergency is highlighting one of Jordan's most pressing problems -- water," said Christian Snoad of Oxfam, in a joint statement with the British Red Cross.