BEIRUT: A rebel alliance including Al-Qaeda's Al-Nusra Front seized more territory in northwestern Syria overnight, strengthening its position on the borders of two key largely regime-controlled provinces, activists said Saturday.

The Army of Conquest rebel alliance had made a series of sweeping gains in Idlib province, said the Syrian Observatory for Human Rights, a Britain-based activist group

Rebels seized a major army position, the town of Muhambel, and several villages in the area between Jisr al-Shughur and Ariha, two key towns already under opposition control.

The 24 hours of fighting left 13 opposition fighters dead along with 32 regime forces, the Observatory said.

The advance cements their control over that part of the province, almost entirely lost by the government, but also allows the grouping to reinforce its positions on the edges of Latakia and Hama provinces.

They are largely regime-controlled, and coastal Latakia in particular is a government bastion and home to President Bashar Assad's ancestral village.

Nusra touted the advances in Idlib on Twitter, listing the "liberation" of several villages and army positions.

State media effectively acknowledged the losses, quoting a military source as saying "the army evacuated several military sites around the town of Muhambel in Idlib province."

"They relocated to new positions and lines more suitable for the implementation of subsequent combat missions," official news agency SANA said.

Regime forces have lost control of nearly all of Idlib province since the Army of Conquest seized the provincial capital at the end of March.

In recent weeks, analysts and observers have said the regime is ready to accept the de facto partition of Syria and is concentrating on holding the areas it considers key and retreating elsewhere.

Elsewhere, the Observatory said nine people were killed -- among them two children -- in rebel rocket fire on the city of Aleppo.

The group said the rockets hit the Ashrafieh district in the western, government-controlled part of the city.

More than 220,000 people have been killed in Syria since the conflict began in March 2011 with anti-government protests that were met with a regime crackdown.