Beirut - Syrian rebels advanced into the contested central Midan district of the country's commercial capital Aleppo, witnesses and military sources said, as combat rocked several city neighbourhoods on Thursday.
"They were at Bustan al-Basha [district] and had already advanced up to Suleyman al-Halabi Street. Now they have entered a street in Midan," one resident said.
Aleppo has been the scene for nearly two months of fierce clashes between regime forces and rebels of the Free Syrian Army (FSA), and Midan is strategic, as it opens the way to the main square.
Elsewhere, several rebel-held districts of the northern city were bombarded, the Syrian Observatory for Human Rights said.
At least 11 people died when a helicopter gunship targeted a crossroads in Tariq al-Bab, the Britain-based Observatory said.
It did not say whether the victims were rebels or civilians, but distributed video footage showing several bodies, some bloodied and others badly burned, in pick-up trucks and on pavements.
In the south of the city, Bustan al-Qasr was bombarded and fighting was reported at Kalasseh, residents said.
A military source also reported clashes between troops and rebels in the western neighbourhood of Saif al-Dawla.
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 killed four people overnight, while troops and rebels battled in the capital Damascus.
It also 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.
The latest killing comes ahead of a visit to Damascus later in the day by the new UN and Arab League peace envoy, Lakhdar Brahimi.