Flights into the Syrian city of Aleppo were reportedly halted as rebels and government forces clashed, preventing planes from reaching the international airport.
Rebels have sought to cut off the country's airports to stop President Bashar Assad's regime from receiving new infusions of supplies and weaponry.
The Syrian Observatory for Human Rights, a pro-opposition group based in London, told the Associated Press that the Aleppo airport had been closed since Monday as fighting raged around a nearby army base.
An unnamed airport official told Agence France-Presse that the airport was closed because of rebel attacks.
"There have been continued attempts by opposition militants to target civilian aircraft, which could cause a humanitarian disaster," the official was quoted as saying.
Syrian rebels have warned that they would target both civilian and military aircraft, claiming that civilian flights were being used to supply the military.
The Syrian military said Monday that it was “continuing the process of clearing the areas surrounding Aleppo International Airport,” according to a statement released by the state-run Syrian Arab News Agency.
State media also reported Tuesday that the armed forces had dealt heavy blows to insurgents in several areas of the country, including Aleppo and the countryside around Damascus and Homs.
Opposition activists reported battles and bombardment throughout Syria. The Syrian Observatory for Human Rights reported that 75 people had been killed Tuesday, more than a third of them government troops. The Local Coordination Committees, an opposition activist network, reported a death toll of 108, including 16 children. The figures could not be independently confirmed.
The nearly 2-year-old Syrian uprising has claimed tens of thousands of lives. Efforts to end the conflict diplomatically have foundered over disagreements over what part Assad would play, if any, in a transitional government.
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