The Syrian government has protested to the United Nations about an air strike by the US-led coalition against Islamic State which it said killed 26 civilians in Hajin in the eastern Deir al-Zor region, state media reported on Saturday.
Asked about reports of air strikes in that area on Friday, the coalition's spokesman said it had "successfully struck and destroyed an ISIS (Islamic State) observation post and staging area in Hajin, void of civilians at the time".
The Syrian Observatory for Human Rights said 41 people, including 17 children, had been killed in two waves of coalition air strikes on Friday in Hajin and the nearby village of al-Shafa on the eastern bank of the Euphrates River.
It said the casualties were mostly Iraqi and family members of Islamic State fighters.
The coalition is supporting the Kurdish-led Syrian Democratic Forces in an attempt to defeat Islamic State in the area it controls near the border with Iraq.
Syrian state media said the foreign ministry had written to the UN secretary general and the president of the Security Council about "the crime" in Hajin.
Colonel Sean Ryan, the coalition spokesman, said: "Our team looks into all strikes to determine the credibility of any civilian casualty claims they see in open media."