ISTANBUL  - Turkey returned fire Friday after a new Syrian shell landed in on its territory close to their common border, NTV private news channel reported.

The Syrian shell landed in the Turkish town of Altinozu in Hatay province near the border, triggering an immediate response fire from Turkish forces, at around 1630 GMT. There were no immediate reports of injuries.

The fresh round of fire exchange comes two days after a Syrian shell killed five Turkish nationals in another border town, Akcakale, triggering a Turkish retaliation fire in its immediate aftermath.

Syrian rebels on Friday said they had captured an air defence base with a cache of missiles outside Damascus, a rare advance on the city after a series of opposition setbacks in the capital. Rebel forces overran the base in the Eastern Gouta area, a few miles east of Damascus, on Thursday, according to video posted on YouTube.

Across the country about 180 people were killed in violence on Thursday, including 48 government soldiers, the British-based Syrian Observatory for Human Rights said.

In New York, the UN Security Council condemned a cross-border mortar attack by Syrian forces that hit a Turkish village and demanded that such violations of international law stop immediately. The video of the assault on the airbase showed dozens of rebels dressed in army fatigues celebrating as black smoke rose from a military installation behind them. It was not possible to independently verify the videos. Access to Syria for foreign journalists is restricted by the Syrian government.

Syrian warplanes also pounded a rebel-held area of Homs on Friday in the heaviest bombardment of the city for months, monitors said.

Rebel fighters hit back by downing a regime helicopter gunship in Damascus province and seizing an army checkpoint outside the eastern city of Deir Ezzor, killing at least 12 troops, said the Observatory.

“Allahu akbar! (God is greatest). The helicopter is falling!” a youth yelled as an aircraft was seen tumbling from the sky in flames on an amateur video that activists posted on the Internet. The Observatory reported five civilians and one rebel killed in the central city and province of Homs, updating its Friday death toll to 64 nationwide - including 28 soldiers, 21 civilians and 15 rebel fighters. In the hill resort of Zabadani, a rebel bastion outside Damascus, two civilians were killed in an army bombardment, the watchdog added.

The army also battered rebel strongholds in Aleppo, Daraa, Deir Ezzor, Idlib and Latakia, said the Britain-based Observatory, reporting clashes in each region. Despite the relentless violence, thousands of people demonstrated across Syria calling for the arming of the rebel Free Syrian Army and condemning the world’s inaction, the Observatory reported.

After hours of haggling between Turkey’s Western allies and longtime Syria backer Russia, the council issued a toughly worded statement, although it was a rung down from a formal resolution. “The members of the Security Council condemn in the strongest terms the shelling by the Syrian armed forces,” it said.

Saying the shelling “highlighted the grave impact the crisis in Syria has on the security of its neighbours and on regional peace,” the statement “demanded that such violations of international law stop immediately and are not repeated.” The Turkish premier warned Syria on Friday it would pay a big price for further attacks and reiterated that Ankara does not want war but is ready to act if threatened by the Damascus regime.

“I am calling once more on the Assad regime and its supporters: Don’t dare to test Turkey’s patience,” Erdogan told a crowd in Istanbul.

The United States said the Turkish fire had been an “appropriate” and “proportional” response, while Russia said the Syrian shelling had been “a tragic accident”. A statement agreed on Friday by the 15-nation council condemned the Aleppo bomb attacks “in the strongest terms” and expressed condolences to families of the victims “of these heinous acts.”