A children's hospital in Aleppo, Syria's commercial hub, used by rebels as an operations base was cleared by government forces, Syrian Radio & TV reported.
The British-based Syrian Observatory for Human Rights and other activist groups said heavy fighting erupted at dawn about three miles from Aleppo International Airport.
Over the past several weeks, rebels have been attacking military airfields in an attempt to prevent them from being used for launching airstrikes, Voice of America reported.
In Homs, government forces reported killing more than two dozen rebels in several operations.
The Syrian Network for Human Rights said it documented the deaths of 23 people Wednesday, including six children.
Fighting in Syria has intensified ahead of a visit by the new international peace envoy later this week. So far, diplomatic efforts to stop the bloodshed have failed.