Government troops have pounded the rebel-held Shaar district of Aleppo, killing 11 people, a rights group said, while 11 others, including seven rebels, were killed elsewhere in Syria's northern city.
"Eleven civilians were killed, three of whose names have been documented, when the army shelled the district of Shaar," the UK-based Syrian Observatory for Human Rights said in a statement on Sunday.
Amateur video posted online showed what appeared to be the streets of Shaar in ruins, with rubble everywhere, electricity cables hanging from buildings, and black smoke rising.
"God curse you, O army," said an unidentified cameraman recording footage in Shaar, his voice trembling. Another video showed bloodied corpses, including at least one child.
The violence came a day after UN and Arab League envoy Lakhdar Brahimi issued a grim warning after meeting President Bashar al-Assad.
Meanwhile, the top commander of Iran's powerful Revolutionary Guard has said that the elite unit has high-level advisers in Lebanon and Syria but remains undecided on whether to send military reinforcements to help save Assad's regime.
Gen. Mohammad Ali Jafari's comments mark the clearest indication of Iran's direct assistance to its main Arab allies, Assad and Lebanon's Hezbollah.
Jafari told reporters that Quds force members have been in Syria and Lebanon as advisers for a long time, but was not more specific.
He said decisions about whether to boost military aid to Syria if attacked would "depend on the circumstances".
A helicopter strike on Sunday on the town of Kafr Aweid in the northwest Syrian province of Idlib killed at least five
children and one woman.
Fresh fighting erupted in the central Midan district, a battleground for more than a week, an AFP correspondent said. The wire service also reported citing a military source, the army shelled Bustan al-Basha just north of Midan and pushed into neighbouring Arkoub after seizing a mosque between the two areas following fierce fighting on Friday.
In-depth coverage of escalating violence across Syria
Violence has raged in Syria's commercial capital since July 20 when government forces launched an offensive aimed at driving rebels out of the city.
In Azimiyeh district, 17 unidentified bodies were found, said the Observatory, which has warned that deaths in Syria are becoming more difficult to document. Elsewhere in the northern province, the watchdog reported one rebel killed
in the town of Al-Bab, while waves of residents fled Al-Safira, fearing a security forces operation.
In Damascus, fighting erupted at dawn in the northeast suburb of Harasta, while the army also shelled the southern suburb of Al-Hajar al-Aswad from several directions.
Explosions also rocked the northeast suburb of Douma, while the rebel Assali and Qadam districts in south Damascus were also bombarded.
The northwestern province of Idlib, where much of the countryside is controlled by the rebels, was also pounded, and at least seven people were killed in an explosion targeting a bus on the road near Khirbet Ghazaleh in the southern province of Daraa.
A similar attack on a bus carrying civilians and troops killed at least four people a week ago in the central province of Homs.
Also in Homs province, shelling killed two civilians in the rebel-held town of Rastan, and a man was killed in shelling in Tal Kalakh bordering Lebanon.
Another man was killed by sniper fire in the eastern city of Deir Ezzor while fighting in the town of Albu Kamal on the Iraqi border killed a woman and a man.
At least 115 people, most of them civilians, were killed on Saturday, according to the Observatory, which gathers its information from activists, medical workers and other sources.