UN humanitarian chief Valerie Amos said in a statement that an unknown number of people are trapped in the city and appealed for safe access to Aleppo for aid groups.
The UN under secretary general said the International Committee of the Red Cross and the Syrian Arab Red Crescent had estimated that 200,000 people have fled Aleppo and surrounding areas in the last two days.
“It is not known how many people remain trapped in places where fighting continues today,” Amos said. Aleppo normally has a population of about 2.5 million people.
Amos said that she was “extremely concerned by the impact of shelling and use of tanks and other heavy weapons” on civilians in Aleppo, Damascus and other locations.