Syrian rebels on Sunday seized control of a sector of Sheikh Suleiman base west of Aleppo, bringing them closer to holding a large swathe of territory extending to the Turkish border in the north.
The rebels took control of Regiment 111 and three other company posts located inside the base after fierce fighting overnight, the Syrian Observatory for Human Rights said.
"Two rebels and one soldier were killed, while five soldiers were captured. The prisoners said that 140 of their men had fled to the scientific research centre on the base," Observatory director Rami Abdel Rahman told AFP.
Sheikh Suleiman sprawls over nearly 200 hectares (500 acres) of rocky hills about 25 kilometres (15 miles) from Aleppo city, an area now almost completely under rebel control.
Elsewhere in northern Syria, 10 were reported killed in regime shelling of the town of Maraayan, while five civilians, including a child, were killed as Ahsam village in Idlib province was shelled, the Observatory said.
The watchdog also reported clashes around the Wadi Daif military base, which rebels have been trying to take since seizing the nearby town of Maaret al-Numan two months ago.
Across the border in Lebanon, meanwhile, sectarian clashes linked to the conflict in Syria killed six people and wounded 40 in the northern city of Tripoli, a Lebanese security official said.
The Observatory said the Syrian army clashed with rebels in the capital's southern Qadam neighbourhood and on the southern and northeast outskirts of Damascus, pressing ahead with its bombardment of rebel-held towns.
Activists posted an Internet video of a large fire in the Port Said area" of Qadam. "The (rebel) Free (Syrian) Army hit the checkpoints," the cameraman says, as machine gunfire is heard in the background.
The military has for several days bombarded rebel strongholds in the suburbs from ground and air, raising fears of a looming ground assault by the army to try to establish a secure cordon around the capital.
The Observatory, which relies on a countrywide network of activists and medics, gave an initial toll of 41 people killed nationwide on Sunday, including 19 civilians.
In all, more than 42,000 people have been killed since the uprising against President Bashar al-Assad's rule erupted in March last year, according to the Observatory's figures.