Syrian warplanes struck against rebels in Idlib province and Aleppo today as fighting raged across the latter.
Rebels and the government blamed each other for the tremendous destruction in Aleppo's medieval heart, including damage to the 12th-century Umayyad mosque.
Islamists say they had driven out government forces using the mosque as a base.
Online videos showed fighters holding partially burned Korans and empty bottles that they said showed troops had been drinking alcohol in the mosque.
The army's version was the opposite, that they had taken the mosque from rebels.
President Bashar al-Assad has ordered the building be repeared immediately, despite fighting in the city centre.
Unesco says five of Syria's six world heritage sites have now been damaged in the civil war.
Aleppo's tourism chief Rami Martini blamed rebels for "targeting the city's monuments and archaeological treasures."
He said centuries-old handwritten Korans had been stolen, as had a box purported to hold a hair of the prophet Mohammed.
Elsewhere, air strikes hit the city of Maaret al-Numan, taken by rebels on October 10.
And shelling in Kfarnebel reportedly killed two children.
Human Rights Watch accused Syrian authorities of using cluster bombs on Sunday, which Damascus denies.
Increasingly heavy weapons are being used by both sides, with the United States admitting today that weapons being funnelled into the country were reaching Islamists.
French authorities said today that European Islamists fighting the Assad government could return to launch terrorist attacks across the Europe.
And the US said on Monday that Lebanese resistance group Hezbollah was fighting for President Assad - which it denies - while reports suggested Iraqi Shi'ites were also travelling to Syria to fight for the government.