Syrian and Russian aircraft pounded rebel-held areas of Aleppo on Friday, a monitor said, after the army announced a new offensive aimed at retaking all of the divided second city.
An AFP correspondent in the opposition-held east of the city reported intense bombardment both from the air and by ground artillery.
It came after the Syrian army announced late on Thursday that it was launching a new offensive to retake rebel-held parts of the city.
A military source said the bombardment was in preparation for a ground operation.
“We have begun reconnaissance, aerial and artillery bombardment,” he told AFP.
“This could go on for hours or days before the ground operation starts.
The timing of the ground operation will depend on the results of the strikes and the situation on the ground.”
An army officer in Aleppo confirmed that the ground assault had yet to begin.
The Syrian Observatory for Human Rights reported at least 30 strikes on rebel-held districts during the night and early on Friday.
The Britain-based monitoring group said at least 10 people had been killed, among them two children, and dozens wounded.
It said more dead were feared buried under the rubble.
