Government troops had been holed up inside the 13th century Umayyad mosque, a UNESCO World Heritage site, in downtown Aleppo for several months before rebels fighting to topple Assad launched a push to liberate it this week.
Activist Mohammad al-Hassan said the army had been using the mosque as a base because of its strategic location in the center of the old city of Aleppo. Rebels and activists have complained that soldiers and pro-government militiamen wrote offensive graffiti on its walls and drank alcohol inside.
But the regime and the rebels are now trading accusations over who is responsible for the fire at the mosque compound adjacent to Aleppo's medieval citadel. Videos posted by activists online show a large fire and black smoke raging inside the mosque on Saturday, and later, its blackened, pockmarked walls. Debris is strewn on the floors where worshippers once prayed on green and gold carpeting.
"Assad's thugs set the mosque on fire as a punishment for being defeated by the Free Syrian Army," the caption on the video read, referring to the rebels fighting to topple Assad. The government on Monday said it pushed back the rebels from the mosque after the weekend fighting, though activists are giving conflicting reports on who controls it.
In another video, a rebel inside the mosque holds up a torn copy of the Muslim holy book, or Quran, saying: "These are our Qurans, this is our religion, our history."
The mosque is the latest victim of the violence plaguing Syria.
On Sept. 29, a fire caused by the fighting swept through Aleppo's covered market, burning more than 500 shops in the narrow, vaulted passageways.
Some of the country's most significant historical sites have been turned into bases for soldiers and rebels, including historic citadels and Turkish bath houses.
In a possible effort to contain the fallout from the damage at the mosque, Assad issued a presidential decree to form a committee to repair the mosque by the end of 2013.
Aleppo has been the scene of intense fighting, particularly since rebels launched a new offensive more than two weeks ago to try to dislodge regime troops. The fighting has devastated large areas of the city of 3 million, Syria's former business capital.
Also on Monday, Turkey forced a plane from Armenia bound for Syria to land to search the cargo for weapons. Foreign ministry spokesman Selcuk Unal said Turkey granted the plane carrying aid for Aleppo permission to fly over its airspace only on condition it can search its cargo for possible military equipment.
After the search, Turkish Deputy Prime Minister Bulent Arinc said the plane would be allowed to continue on to Syria. He said the cargo contained humanitarian aid as stated.
Turkey forced a Syrian passenger plane flying from Moscow to Damascus to land in Ankara last week. Turkey said the Syrian Air plane was carrying military gear while Russia said that the equipment was spare parts for radar systems.