BEIRUT — Syrian President Bashar Assad ordered on Monday immediate repairs to a historic mosque in the city of Aleppo after fierce fighting between rebels and regime forces set parts of the compound on fire over the weekend.

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.