Air strikes by US-led forces in Syria have killed 865 people, including 50 civilians, since the start of the campaign in late September against Islamic State militants, a group monitoring the war said on Wednesday.
The Britain-based Syrian Observatory for Human Rights said the majority of the deaths, 746, were Islamic State fighters and that the actual figure could be much higher. Islamic State has seized tracts of territory in Syria and neighbouring Iraq, where it has also been targeted by US-led forces since July.
Eight of the civilians killed were children, the Observatory said. It said 68 members of al Qaeda-affiliated Nusra Front were also killed in the air strikes, which started early on September 23.
Coalition strikes have hit the Syrian provinces of Aleppo, Deir al-Zor, Hasaka, Raqqa and Idlib, the Observatory said.
The United States has said it takes reports of civilian casualties seriously and says it has a process to investigate each allegation.
Washington justified its action in Syria under Article 51 of the UN Charter, which covers an individual or collective right to self-defence against armed attack.
Around 200,000 people have been killed in Syria's conflict, which is now in its fourth year, according to the United Nations.