Syrian state media say U.S.-led coalition aircraft have bombed pro-government forces near the border with Iraq, leaving a number of people dead.
Citing a military source, the June 18 reports said the attack targeted a position in the village of Al-Huri in Deir al-Zor Province.
It said several people were killed and others wounded in the strike.
A coalition spokesman denied carrying out any strikes in the area.
The Britain-based Syrian Observatory for Human Rights said 38 foreign fighters allied with the government of President Bashar al-Assad died in the bombing.
Iraq's Popular Mobilization Forces, a grouping of mostly Shi'ite paramilitaries, said the strike killed 22 of its members and wounded 12 others.
Pro-government forces, supported by Russia and Iran, and a U.S.-backed alliance of Kurdish and Arab fighters are both battling the Islamic State (IS) extremist group there.
Thousands of Shi’ite militiamen armed and trained by Iran are reportedly fighting in Syria.