Syria's bloodiest day claims over 305 lives
"This is the highest toll in a single day since March 2011. And this is only counting those whose names have been documented. If we count the unidentified bodies, the figure will be much higher," director of Syria's Observatory for Human Rights Rami Abdel Rahman told Agence France-Presse by telephone.
A total of 199 of Wednesday's dead were civilians, the UK-based watchdog said.
In the east city of Deir Ezzor, 23 people including a child were killed by army gunfire when troops stormed the Jura district.
In Damascus, 17 people including three children were shot dead in the north Barzeh neighbourhood, the watchdog said.
Another 14 people were killed when two bombs struck the Syrian army headquarters in the heart of Damascus, according to the Observatory.
Outside the capital, 40 bodies, including those of children, were found in the village of Diabeya.
The previous highest death toll of the uprising was on July 19, when 302 people were killed, according to the Observatory.
More than 30 000 people have been killed in violence since the outbreak of the revolt against the rule of Syria's President Bashar al-Assad in March last year.