A cluster bomb hit a school playground in a village just outside the Syrian capital Damascus, killing as many as 10 children as they played, opposition activists said.

The strike in the village of Deir al-Asafir came just hours after rebels seized a key military airbase in the area, leading to speculation that the government was taking retribution as it attempts to keep a grip on power in the face of mounting rebel gains. Reports also suggested that those opposed to Bashar al-Assad's government also took a hydroelectric dam yesterday in the east of the country.

A graphic video posted online appears to show the chaotic aftermath. A young girl in a purple jumper lies motionless on the floor, with another limp body of a girl dressed in red splayed out next to the school gates. The cameraman moves to a car where the corpses of two young boys have been piled in the back seat. He pans back to the girls where a woman in a headscarf kneels over the body of one of them, screaming.

The Syrian regime has denied using cluster munitions, saying it does not possess them, but their use has been documented by human rights groups and activists with increasingly frequency. Controversial because of their indiscriminate nature, the ordnances scatter mini "bomblets" over an area the size of a football pitch and those that do not explode can become effective land mines, maiming and killing for decades.

Another video from Deir al-Asafir showed bomblet casings gathered by the villages, with one man saying that 70 bomblets had been found. Activists denied reports that rebel fighters were hiding out in the village.

The London-based Observatory for Human Rights put the death toll at eight, while others said 10 children had died. "None of those killed was older than 15 years old," said Abu Kassem, an activist from the village.

The regime's fighter jets also struck targets near the Turkish border yesterday, sending refugees stuck in makeshift camps fleeing for their safety. The missiles fell near the Atmeh refugee camp, home to more than 10,000 Syrians who have fled from elsewhere in the country.

Turkey's state-run Anadolu Agency said airstrikes had killed and wounded several people in the border village, but no further details were given.

The attack appeared to have targeted a Free Syrian Army base nearby, but missed. "Two Syrian fighter jets came and fired five rockets. Three have hit farm areas and another two hit buildings near the base," said one local activist named Ahmed.

The strikes come a day before a joint Turkish-Nato team will begin scouting locations along the border to decide on the locations for the deployment of a surface-to-air Patriot missile system, which Turkey hopes will protect from attacks from within Syria's borders. "That it will be used to form a no-fly zone or for an offensive operation is out of the question," the Turkish military said in a statement. There were unconfirmed reports yesterday that Turkey had scrambled fighter jets to the border after the shelling just metres from its territory.

After days of fighting rebels also captured a key hydroelectric dam on the Euprates River in the north of the country yesterday. The dam supplies electricity to several areas of Syria and its loss was described by Observatory director Rami Abdul-Rahmanas as a "major blow" to the regime.

Amateur videos posted online showed gunmen inside the dam's operations room as an employee sat in front of five screens speaking by telephone about the level of water behind the dam. Another video showed a gunman in front of dozens of green wooden boxes apparently full of munitions. A gunman opened one of the boxes showing that it contained hand grenades.

"The Free Syrian Army has fully liberated the Tishrin Dam," one of the rebels could be heard saying.