Amnesty International has accused the militant Islamic State group of carrying out a systematic campaign of mass killings, abductions and ethnic cleansing in northern Iraq that could amount to war crimes.

The London-based rights group says the extremists, who in June overran parts of northern and western Iraq, have systematically targeted religious minorities.

In a report Tuesday, Amnesty says the Islamic State group fighters expelled Christians, Shiites, Yazidis and others from their homes.

The report documents several cases where the militants carried out mass killings of Yazidi men, rounding up men and boys and killing them in groups.

The report also documented the abduction of hundreds of Yazidi women and children. It says the fate of most of the abducted women and children is still unknown.