"At least seven civilians, including six children, were killed by regime forces shelling of the besieged town of Herak," said the Syrian Observatory for Human Rights.
The Britain-based group distributed a video showing the bodies of dead children, including a young girl in a pink and white dress, lying on a blood-smeared floor, some of their faces covered in blood.
"Herak has been under shelling for 10 days," an unidentified man says in the amateur footage. "The world is watching. Where are the Arabs and Muslims when these children are killed during Ramadan?" he pleaded, referring to the holy month of fasting.
"Bashar, I hope your children will suffer the same fate," he screamed, addressing President Bashar al-Assad. The Observatory said eight people were killed when forces put down a prison mutiny in Aleppo, which followed a similar rebellion at the main prison in the central city of Homs.
An inmate, who said he had smuggled a mobile phone into the prison, told AFP: "The situation after the security forces came in is horrifying. All I can hear is the sound of screaming.
"They are viciously torturing the detainees who they suspect of leading the mutiny," the man added. Fighting raged in Aleppo, with the Observatory reporting clashes between troops and rebel fighters in the Sukari, Sakhur and Hanano neighbourhoods.
A spokesman for the rebel Military Council told AFP yesterday that opposition fighters had "liberated" multiple neighbourhoods of the city, including Salaheddin, as the army continued to bombard the districts.