Nine children were among at least 15 people killed in an air strike on a mainly Kurdish district of the northern Syrian city of Aleppo on Saturday, a watchdog said.

"The number of people killed in an air strike on the western edges of Sheikh Maksoud has risen to 15 ... Among them were nine children aged under 18 years and three women," said the Syrian Observatory for Human Rights.

It was not immediately clear if any of the casualties were fighters from the Democratic Union Party (PYD), Syria's branch of Turkey's outlawed Kurdistan Workers' Party (PKK), the Britain-based Observatory said.

After the strike, Kurdish fighters killed five soldiers in an attack on an army checkpoint, the watchdog added.

Up until now, Syria's Kurds have been split over their country's anti-regime uprising, with most trying to maintain neutrality.

Amateur video distributed by the Syrian Revolution General Commission, an activist network, showed burnt bodies lying in rubble, reportedly filmed after the strike.

The video shows a woman screaming as she picks up the body of a young girl from the ground.

Elsewhere in Syria, the air force targeted Al-Hajar al-Aswad in southern Damascus and Qadam in the southwest, said the watchdog, which relies on a broad network of doctors, lawyers and activists for its reports.

Al-Hajar al-Aswad was also struck by mortar rounds and rockets, activists in the capital said.

Warplanes also raided Yabrud near Damascus and Qusayr in the central province of Homs, as tanks shelled rebel enclaves in Homs city.

In Damascus, mortar rounds hit Baramkeh in the heart of the capital, said the Observatory, as rebels pressed their campaign to break into the regime's key bastion.

Saturday's violence came a day after at least 94 people were killed across the country -- 32 civilians, 36 rebels fighters and 26 soldiers -- according to an Observatory count.

The UN says more than 70,000 people have been killed in Syria's two-year conflict, which broke out after the army unleashed a brutal crackdown against dissent, turning the uprising into a bloody insurgency.