Russian Prime Minister Dmitry Medvedev slammed as "unacceptable" the recognition and support by France and other states of the Syrian opposition battling the regime of President Bashar Assad.

In a wide-ranging interview with Agence France-Presse and Le Figaro ahead of a visit to Paris starting Monday, Medvedev also spoke of the EU economic crisis as a "serious threat" and did not rule out returning to the Kremlin in the future.

Syrian rebels on Sunday seized the training camp of a pro-regime Palestinian faction near Damascus after fierce clashes, a watchdog reported.

"Rebels stormed a Popular Front-General Command (PFLP-GC) training camp in the Rihan area of Damascus province, after violent clashes with local fighters," according to the Syrian Observatory for Human Rights.

Syrian troops on Sunday bombarded the outskirts of Damascus, where monitors said almost 50 people died in a battle for a military airport, as the country's 20-month conflict homes in on the capital.

Russia and France, meanwhile, prepared for talks on Tuesday in Paris at which Russian Prime Minister Dmitry Medvedev and France's President Francois Hollande are expected to address differences over the Syria conflict.

Four British Islamist extremists are being trained to fight in Syria at a camp run by radical Islamist preacher Omar Bakri in northern Lebanon, Britain's The Sun newspaper reported on Sunday.

Bakri boasted of his “military-style courses for Islamic fanatics on the lawless border with Lebanon,” The Sun said.

Jordan on Sunday opened a Bahrain-funded school in the Zaatari refugee camp near the Syrian border that can take up to 4,000 students, a Jordanian official said.

Jordan's education ministry and the U.N. children's fund UNICEF jointly run the school, in which 3,400 Syrian refugees are currently enrolled and taught by Jordanian and Syrian teachers.

Iranian parliament speaker Ali Larijani met Turkish Prime Minister Recep Tayyip Erdogan behind closed doors in Istanbul for two hours on Saturday, Turkish news agency Anatolia reported without providing details.

Larijani is on a regional tour, having already been to Syria and also planning to visit Lebanon.

Syrian rebels attacked army positions in the northern province of Aleppo on Saturday while Islamist fighters clashed with Kurdish militias on the border with Turkey, residents said.

Insurgents also attacked troops guarding the strategic Tishrin dam, located on the Euphrates river between the provinces of Aleppo and Raqa.

Rebels who have besieged Sheikh Suleiman army base for nearly two months are confident it will fall in days, giving them full control of a swathe of northwest Syria from Aleppo to the Turkish border.

Their optimism has been buoyed by a steady stream of defectors from the ranks of the several hundred troops defending the strategic base, the last major garrison still in army hands between the border and Syria's northern metropolis.

NATO Secretary General Anders Fogh Rasmussen sought Friday to reassure Russia over the requested deployment of Patriot missiles in Turkey near the border with Syria, saying it would be a "defensive only" measure.

NATO spokesman Carmen Romero said Rasmussen had told Russian Foreign Minister Sergei Lavrov in a telephone conversation that such a deployment "would in no way support a no-fly zone or any offensive operations."

Turkey's request to site Patriot missiles on its border with Syria only "complicates" the conflict in the Arab country, Iran's foreign ministry said on Friday.

"Not only does it not help resolve the situation in Syria but it will also aggravate and complicate the situation," ministry spokesman Ramin Mehmanparast said, quoted on state television.