Bukulmez, Turkey: Syrian warplanes bombed a rebel headquarters near the Turkish border on Monday, missing their target but sending hundreds of Syrians fleeing across the frontier.
The attack on the Free Syrian Army base in Atima, 2 km (1 mile) from the border, came a day before Turkish and NATO officials were due to start assessing where to station surface-to-air missiles close to the 900 km (560 mile) border.
Turkey, a major supporter of insurgents fighting to oust President Bashar al-Assad, has repeatedly scrambled jets along the joint border and responded in kind when Syrian shells have landed inside Turkey.
But Ankara, rejecting Syrian complaints that the Patriots were "provocative", stressed they would be used only to defend Turkish territory, not to create a no-fly zone inside Syria that rebels want to neutralise Assad's massive air power.
Describing the bombing of the FSA base, opposition activist Ahmed, who lives within a few blocks of it, said: "Two Syrian fighter jets came and fired five rockets. Three have hit farm areas and another two hit buildings near the base."
Monday's strike was one of the closest to the Turkish border carried out by Syrian jets. Ahmed said it was the first time they targeted the FSA base set up by senior rebel Mustafa al-Sheikh when he crossed over to Syria from Turkey two months ago.
Rebels fired anti-aircraft guns at the jets but they were flying too high to be hit, activists said. "I think the reason for the raid may have something to do with increased weapons movements (from Turkey)," Ahmed said.
Several hundred Syrians fled into Turkey after the raid and were being taken care of by the Turkish army. At least two wounded people were taken across the border.
The Turkish Anatolian news agency said an anti-aircraft shell fired during clashes in another Syrian border town, Harem, hit the roof of a house in the Turkish district of Reyhanli, causing no casualties.
After 20 months of conflict, rebels have been tightening their hold on farmland and urban centres to the east and northeast of Damascus, and have seized a string of military bases in the past 10 days.
A joint Turkish-NATO team will start work on Tuesday assessing where to put Patriot missiles, how many will be needed and the number of foreign troops to be sent to operate them.
Turkey is reluctant to be drawn into the fighting, but the proximity of Syrian bombing raids to its border is straining its nerves. It is worried about its neighbour's chemical weapons, the refugee crisis on its border, and what it says is Syrian support for Kurdish militants on its own soil.
Activists say more than 40,000 people have been killed in Syria's civil war, which started with peaceful demonstrations for reform but grew into demands for the overthrow of 42 years of dynastic rule by Assad and his late father, Hafez al-Assad.
Attacks by mainly Sunni Muslim rebels against Assad's forces have become increasingly effective and deadly. The president, from Syria's Alawite minority which is linked to Shi'ite Islam, has responded with devastating artillery and air bombardment.
Hundreds of thousands of Syrians have fled their country and more than 2 million more have been displaced. The opposition said last week $60 billion would be needed for reconstruction.
The military installations rebels have captured in the last 10 days include a major facility in the northern province of Aleppo and several bases around the capital Damascus.