The UN has urged US-led coalition forces to suspend their assault on Raqqa, and permit evacuation.
The organization reported that up to 25,000 civilians were thought to be trapped in the city which, according to the coalition, had been hit by 250 air strikes in the past week alone.
Hundreds of civilians have been killed since the assault started in June, Amnesty International estimates.
However, Lt Gen Stephen Townsend, commander of the coalition, said in Baghdad on Tuesday that he had not seen “hard information that says that civilian casualties have increased in Raqqa to some significant degree”.
In addition to the air strikes, the Syrian Democratic Forces (SDF) alliance is shelling targets in the city from the ground.