The activists said the Free Syrian Army seized Taftanaz airport, northeast of Idlib, a base for helicopters that bomb rebel-held areas in the north, the BBC reported.
U.S. and Russian officials were in Geneva, Switzerland, Friday to meet with Bakhdar Brahimi, U.N. special envoy to Syria, to discuss how to move forward on a peace plan proposed by world leaders in June. Russia and the United States disagree on the opposition's demand that President Bashar Assad step down.
Free Syrian Army fighters, led by the jihadist groups al-Nusra Front, Ahrar al-Sham and the Islamic Vanguard, had surrounded Taftanaz Military Airport for weeks, the BBC said. Rebels stormed the air base Wednesday and by Thursday seized control of more than half of it.
On Friday, the Local Coordination Committees, an opposition activist network, said the Free Syrian Army was in full control at the base.
The LCC said a government warplane later bombed the nearby town of Taftanaz.
The Syrian Network for Human Rights said it documented the deaths of 43 people Thursday across Syria, including four children, two women, and two people tortured to death. Eighteen deaths were reported in the Damascus area and 10 were reported in Aleppo.
In Geneva, Brahimi's talks with U.S. Deputy Secretary of State William Burns and Russian Deputy Foreign Minister Mikhail Bogdanov will include ways to implement the agreement that provides for the formation of a transitional government to end the conflict that began in March 2011, and in which the United Nations estimated 60,000 people have died.
On Sunday, a defiant Assad condemned "foreign meddling" and vowed to remain power, The New York Times said.
On Thursday, the Syrian government accused Brahimi of "flagrant bias" for hinting that Assad would have to leave, the Times said. The veteran Algerian diplomat, speaking to journalists after Assad's speech, said "surely he [Assad] would not be a member" of a transitional government.
Syria's Foreign Ministry said Brahimi's remarks showed he "is flagrantly biased for those who are conspiring against Syria and its people."