BEIRUT — Syrian rebels fought pitched battles Wednesday against regime forces at a military base that protects a major airport in the country's north in fighting that has left more than 40 government troops dead, opposition activists said. Rebels have been attacking the civilian airport in the city of Aleppo for weeks, and now appear to have overrun the main defenses around the facility. But the airport itself, which stopped handling any flights weeks ago because of the fighting, still remains in regime hands. On Tuesday, opposition fighters captured large parts of the “Brigade 80” base near the airport and attacked another major air base, Nairab, adjacent to the international airport after taking control of Al-Manara army checkpoint just outside it. By Wednesday, the Britain-based Syrian Observatory for Human Rights said the rebels were “almost fully in control” of the “Brigade 80” base. He said more than 40 government troops were killed in the fighting, including two brigadier generals, a colonel and two lieutenant colonels. The report could not be independently confirmed. Heavy clashes were also still raging for control of the Nairab base as well as outside the civilian airport, which both have their own defenses in addition to the protection provided by Brigade 80. Abdul-Rahman said the brigade is an air defense force that's main task is to protect the international airport and the Nairab air base. Syria's rebels have notched several of strategic victories in recent days, capturing a military air base in the province of Aleppo on Tuesday and the country's largest dam on the Euphrates River the day before. With the back-to-back blows to President Bashar Al-Assad's regime, opposition fighters appear to be regaining some momentum in the nearly 2-year-old conflict, expanding their northern zone of control while at the same time pushing deeper into the heart of the capital, Damascus. Activists reported clashes outside Damascus Wednesday, with regime warplanes hitting several of the restive suburbs as part of a government offensive to dislodge opposition fighters from their strongholds around the capital. Fighter jets also carried out airstrikes on rebel positions in the central province of Homs, the observatory said. The rebels have been pushing their way into Damascus since last week, and came to within a mile of the heart of the capital on Friday. The foray marks the opposition's second significant attempt to storm Damascus since July, when the rebels captured several neighborhoods before being swept out by a swift counteroffensive. — AP