Syria's second city is at the heart of clashes between pro-government forces and a range of insurgents, including al Qaeda's Syria wing, "Islamist brigades" and Western-backed rebels.

The United Nations Syria envoy Staffan de Mistura is seeking a local ceasefire in Aleppo to allow badly-needed humanitarian assistance into the divided northern city.

Pro-government forces captured an area east of al-Malah farms outside Aleppo and is now aiming to secure parts in the west and cut off insurgent supply lines into the city, the Britain-based Syrian Observatory for Human Rights said.

It said 34 fighters from "Islamist groups" including al Qaeda's Nusra Front were killed when Syrian army attacked their positions with backup from local pro-government forces.

It added that there were also battles south and east of the city.

Syria's state news agency said the army was tightening its "grip on terrorists in Aleppo after new advances."

It said pro-government forces had captured all of the al-Malah area as well as areas south and west of Handarat town in the countryside and reported that a "huge number" of enemy fighters had been killed.