At least 11 people were killed early on Thursday in an air strike by government forces on a district of Syria's commercial capital and second city Aleppo, the Syrian Observatory for Human Rights said.
The latest violence comes ahead of a visit later in the day to Damascus by the new UN and Arab League peace envoy, Lakhdar Brahimi.
In Aleppo, the scene for nearly two months of fierce clashes between regime forces and rebels of the Free Syrian Army (FSA), several rebel-held districts of the northern city were bombarded, the watchdog said.
At least 11 people died when a helicopter gunship targeted a crossroads in the city's eastern district of Tariq al-Bab, the Britain-based Observatory said.
It did not say whether the victims were rebels or civilians. It distributed video footage showing several bodies, some bloodied and others badly burned, in pick-up trucks and on pavements.
The Local Coordination Committees group (LCC), which organises anti-regime protests on the ground, said the military also used artillery against the Fardoss district of the city, in a heavy barrage.
The Observatory earlier reported that bombing in the Karam al-Jabal region of Aleppo province also killed four people overnight, while troops and rebels battled in the capital Damascus.
It said a former MP, Ahmad al-Turk, was shot dead by security forces who raided his house in Harasta in Damascus province at dawn and arrested his son.
The Observatory also said a car bomb exploded in the Rokn Eddin neighbourhood of the capital, without causing any casualties, while there was also shelling in Tadamun.
LCC activists also reported heavy fighting overnight between regime forces and rebels of the Free Syrian Army in the Qaboon district of the capital.
Violence nationwide in Syria on Wednesday claimed the lives of 129 people -- 70 civilians, 42 soldiers and 17 rebels -- according to Observatory figures.