An Iraqi Shi'ite militia says dozens of its members have been killed in an attack on its positions near the Syrian border.
The Iran-backed Kataib Sayyid al-Shuhada militia said on August 8 that more than 30 of its fighters were killed and at least 75 others were wounded in the attack.
The group, which is part of the Iraqi government-allied Popular Mobilization Forces, said U.S. aircraft were to blame for the August 7 attack, adding that "this action will not pass unpunished."
However, the U.S.-led coalition denied its forces had been involved.
Iraq's Prime Minister Haidar al-Abadi said at a news conference in Baghdad that an initial investigation showed the Islamic State launched the attack against the Shi'ite militia.
The extremist group said on August 7 that it killed scores of Iraqi soldiers in an attack in the area.
Iranian-backed militia and the U.S.-led coalition are fighting separate campaigns against the IS group in Iraq.
IS fighters lost Mosul in June but still control territory in three areas located southeast, west, and southwest of the northern Iraqi city.
Based on reporting by AP, Reuters, and the BBC