59 civilians have been killed after US-led coalition air strikes hit the Syrian city of Raqqa over three days, according to the British monitoring group.
The Syrian Observatory for Human Rights said 21 children were among the dead on Thursday .
The airstrikes are intended to weaken ISIL militants' hold on the city and the coalition claims it takes every precaution to avoid civilian casualties.
It has admitted 624 such deaths in its air strikes since 2014, a figure that independent monitors say is vastly under-estimated.