Activists in Syria said a government jet yesterday dropped a cluster bomb on a playground, leaving 10 children dead, reported BBC.
Video posted on the internet showed children's bodies on the ground with their mothers grieving over them.
The children were killed when a MiG fighter bombed a playground in the village of Deir al-Asafir, east of Damascus, opposition activists said.
Intensive fighting has continued around the capital. Rebel fighters captured at least part of an airbase yesterday.
Further footage of the playground attack showed what appeared to be cluster bomblets on the ground.
Syrian rebels yesterday said they had captured a helicopter base east of Damascus after an overnight assault, their latest gain in a costly battle to unseat President Bashar al-Assad that is drawing nearer to his seat of power, reports Reuters news agency.
The Marj al-Sultan base, 15 km from the capital, is the second military facility on the outskirts of the city reported to have fallen to Assad's opponents this month.
Activists said rebels had destroyed two helicopters and taken 15 prisoners.
In one video, two girls could be seen lying dead in a street while another showed a distraught mother standing, apparently inside a clinic, over her daughter's lifeless body.
Syrian rebel officers have formed a commission to lay the foundations for a future army and liaise with the political opposition on issues such as arming fighters on the ground, a spokesman yesterday said, reported AFP.
The announcement came in a video posted to YouTube on Sunday which shows some 50 Free Syrian Army officers wearing military fatigues assembled in a dimly lit basement room, one of whom reads a statement listing the objectives and basic principles agreed on during their gathering.
In recent months there have been mounting allegations that the Syrian government has resorted to using cluster bombs as the conflict intensifies, although those claims have been denied, the BBC's Jim Muir in neighbouring Lebanon reports.
Two cluster bombs were dropped on the village, activists said. One man told Reuters news agency that 70 bomblets had been found.
"None of those killed was older than 15 years old," Abu Kassem, an activist in Deir al-Asafir told Reuters.
He said 15 people had been wounded in the attack and denied that rebel fighters were inside the village. They had been operating on the outskirts, he said.
Last month, Human Rights Watch said there had been an increase in online video reports purporting to show evidence of cluster bombs being dropped in the conflict, especially around the town of Maarat al-Numan.