Syria conflict: Regime 'kills dozens' in Damascus
Syrian government forces launched two operations in Damascus to root out rebel activists on Wednesday, killing at least 70, the opposition has said.
Troops reportedly went from house to house demanding to see people's papers, and summarily executed many of their victims, according to activists.
Syrian state TV said "dozens of terrorists" surrendered or were killed in the operation.
Meanwhile, rebels said they attacked an airport near the second city of Aleppo.
Opposition commanders said they used a tank captured from the army to bombard the Menagh air base, which lies between Aleppo and the rebel-held town of Azaz near the Turkish border.
They said government forces had used the air base as a staging post for attacks on nearby areas.
The fighting in Aleppo city appears to have settled into a stalemate.
State TV, which had initially forecast that the city would be cleared of rebel fighters in just a few days, is now reporting only a few clashes with "terrorist mercenaries."
The BBC's Jim Muir in neighbouring Lebanon says the momentum seems to be with the rebels, who have managed to open a direct corridor to the Turkish border.
He says they are clearly bent on making Aleppo the heart of a "liberated zone" in the north, which would hugely increase pressure on the government in Damascus.
But some of the rebels' tactics are proving controversial.
Video posted online shows rebel gunmen killing several prisoners who were said to belong to a pro-government militia in the city of Aleppo.