A leading international rights group has criticized Syrian government bombings last November that targeted the de-facto capital of the Islamic State group, saying the airstrikes killed dozens of civilians and may amount to war crimes.

Amnesty International said in a statement released on Tuesday that it has documented a series of Syrian government airstrikes between Nov. 11 and Nov. 29 that killed up to 115 civilians in the city of Raqqa in northern Syria. On Nov. 25, at least 60 people died there.

Amnesty says the "unlawful" killings violated international humanitarian law and that some of the attacks may amount to war crimes.

Raqqa has been the seat of the Islamic State group since it declared a caliphate in areas under its control in Iraq and Syria.