Members of al Qaeda wing Nusra Front and other Sunni Islamist battalions seized an area south of a Shi'ite Muslim village in northern Syria on Sunday after deadly clashes with pro-government fighters, a group monitoring the war said.
The fighters advanced overnight on al-Zahra, north of Aleppo city, seizing territory to the south and also trying to take land to the east in an attempt to capture the village, the Britain-based Syrian Observatory for Human Rights said.
Al-Zahra and the nearby village of Nubl have been under a long siege by anti-government forces in an isolated Shi'ite area. The United Nations said in March that armed groups surrounding the villages had cut electrical and water lines supplying 45,000 residents.
The villages are located along a highway that leads to Turkey and is a supply route to Aleppo.
An opposition spokesman said in January that the area had been surrounded because it had been used as a launching pad by the Syrian military to attack Aleppo. The opposition said at the time it could lift the siege if the Syrian military reciprocated elsewhere, but this had not happened.
The clashes killed at least eight of the fighters advancing on al-Zahra and a number of fighters from the pro-government National Defence Force, the Observatory said.
Aleppo and surrounding areas have been hit by heavy fighting in a conflict which is now in its fourth year and has killed some 200,000 people according to the United Nations.
The world body's Syria mediator has said that Aleppo would be a good starting point for local ceasefire agreements and has discussed the idea with President Bashar al-Assad.