Battles in and around the Syrian city of Aleppo have killed at least 70 pro-government fighters and more than 80 insurgents after the army launched an offensive there, a monitoring group said on Wednesday.
The army backed by allied militia had captured areas north of Aleppo on Tuesday in what the Syrian Observatory for Human Rights said was an attempt to encircle the northern city and cut off insurgent supply lines.
Aleppo is at the forefront of clashes between the army and a range of insurgents, including Islamist brigades, al Qaeda's Syria wing Nusra Front and Western-backed units battling President Bashar al-Assad.
The United Nations is seeking a ceasefire there, a step towards addressing the crisis in Syria which is about to enter its fifth year.
The advance on Aleppo is the second major offensive by pro-government forces in a week. The army and allied combatants from Lebanon's Hezbollah group have also launched a large-scale assault in southern Syria against insurgents.
On Wednesday the main route leading north out of Aleppo to the Turkish border was blocked and under fire by pro-government forces, the Observatory's founder Rami Abdulrahman said.