The Syrian Observatory for Human Rights, a monitoring group, said some 2,000 pro-regime fighters from Syria, Iraq, Iran and Lebanese Shiite movement Hezbollah had arrived in Aleppo since late Sunday.
"Both sides are amassing their fighters in preparation for the great battle of Aleppo," said Rami Abdel Rahman, the head of the Britain-based observatory.
The Monday edition of Al-Watan, a Syrian daily close to the government, reported that the army had received "the necessary military reinforcements to
launch the battle to retake the areas from which it withdrew."
Citing a source on the ground, the paper said military warplanes "are carrying out a barrage of air strikes targeting the armed groups."