US investigators have said airstrikes conducted by American forces on Isis in Raqqa have produced a "staggering" loss of life among civilians.
America is backing a coalition of Kurdish and Arab fighters which have begun a siege of the city to free it from the clutches of Islamic State.
Since the assault began, roughly a week ago, the Syrian Democratic Forces (SDF) have managed to take back key ground from the terrorists.
US forces are providing air support for the ground troops, and have been conducting airstrikes on the terror group's stronghold.
Now, war crime investigators based in the US have said the strikes have caused a "staggering" loss of civilian life.
More than 160,000 people have already fled their homes in the city as the fighting draws closer.