Beirut/Akcakale - Syrian rebels 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 U.N. 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.
Turkish artillery bombarded Syrian positions on Wednesday and Thursday in retaliation but the border area appeared to be quiet on Friday.
The incident underscored how the conflict, now in its 19th month, could flare across the region while Thursday's fighting showed the situation inside Syria was only getting more serious.
More than 30,000 people have been killed in the uprising against President Bashar al-Assad, which began with peaceful street protests but is now a full-scale civil war.
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.
A middle-aged man holding a rifle says the attack was carried out by a rebel battalion from the town of Douma. It also showed rebels at a weapons cache which included what appeared to be part of a surface-to-air missile.
It was not possible to independently verify the videos. Access to Syria for foreign journalists is restricted by the Syrian government.
When rebels have captured army bases in other parts of the country, war planes have bombed the sites shortly afterwards.
Although fighting often takes place in the Damascus suburbs, rebel forces have been unable to hold areas for long in the face of government artillery and air power. They have staged devastating bomb attacks on government and military offices in the heart of the city, however.
Turkey talks tough
Turkey has made clear it is ready to launch retaliatory strikes again if the war spills over the border but it has also said it will act under international law and in coordination with other foreign powers.
This week's cross-border violence was the most serious so far in the conflict.
Five Turkish civilians were killed in the south-eastern town of Akcakale by the Syrian mortar attack. The Turkish salvoes killed several Syrian soldiers.
Turkey's parliament on Thursday authorised cross-border military action in the event of further aggression. Prime Minister Tayyip Erdogan said Ankara would never want to start a war and the parliamentary vote was merely a deterrent.
But people in the region remained fearful.
Turkey is sheltering more than 90,000 refugees from Syria and fears a influx similar to the flight of half a million Iraqi Kurds into Turkey after the 1991 Gulf War.
Syria's ally Russia said it had received assurances from Damascus that the mortar strike had been a tragic accident.
The U.N. condemnation was issued after two days of negotiations on an initial text rejected by Russia.
Consensus within the council on Syria-related matters is unusual and it has been deadlocked over the conflict, with veto-wielding Russia and China rejecting calls to sanction the Damascus government.