Fierce clashes have broken out on the edge of the northern city of Aleppo, a day after rebels overran a nearby air base, while a deadly blast rocked Raqa city and reports said 60 rebels had been killed in an ambush.
"Fierce clashes pitting rebels ... against regime forces broke out near the airforce intelligence building in the Layramun area on the edges of Aleppo," said the Syrian Observatory for Human Rights on Wednesday.
The monitoring group said the rebels engaged in the battle were Islamists, among them the jihadist Al-Nusra Front.
The battle comes a day after rebels overran the air base at nearby Minnigh.
An activist in Aleppo said rebels were trying to advance towards Nabul and Zahraa, majority Shi'ite villages in the Aleppo countryside that have turned into bastions of President Bashar al-Assad's regime.
Most of Syria's rebels - like the population - are Sunni, while Assad belongs to the Alawite community, an offshoot of Shi'ite Islam.
"Some 300 fighters who had been fighting for Minnigh are now free to fight elsewhere," said Mohammed, an activist with the anti-regime Aleppo Media Centre.
Elsewhere, an explosion ripped through the northern city of Raqa, Syria's only provincial capital to have fallen out of regime control, killing three people including two children, said the Observatory.
The Britain-based group said the origin of the explosion has not been identified, and added that dozens of people were wounded.
Near Damascus, Syrian troops killed at least 62 rebels in an ambush on Wednesday, the observatory said.
The Syrian military said those killed were members of the jihadist Al-Nusra Front.
"At least 62 rebels fell as martyrs, most of them youths, and eight others are missing after an ambush by regime forces at dawn near the industrial city of Adra," northeast of the capital, the monitoring group said.
A Syrian military source quoted by state news agency Sana said the "army carried out an ambush on a group of terrorists belonging to the Al-Nusra Front that was trying to infiltrate Eastern Ghuta and attack a military post."
"All the terrorists were killed and their arms captured," the source added, without giving a toll.
Adra, 35 kilometres from Damascus, is the gateway to Eastern Ghuta, a farming region where a large number of rebels are located.
Nearby, the air force staged two air strikes on the battered town of Douma, where anti-regime sentiment has been strong since early in the anti-Assad revolt, which broke out in March 2011.
