ISTANBUL — The Pentagon said Saturday it had halted an airstrike on Syria after Russia and the Syrian government accused U.S. warplanes of responsibility for killing 60 Syrian soldiers.

In a statement, the U.S. military’s Central Command admitted it had been carrying out a strike against a suspected Islamic State position in the eastern province of Deir al-Zour, but said it called off the assault after Russia said it was Syrian army positions that were being attacked, and not the Islamic State.

Earlier Saturday, Syria and Russia had accused the U.S.-led coalition of striking a Syrian army base and blamed the raid for an Islamic State advance in the area.

Saturday’s developments come amid an already fragile cease-fire brokered by Russia and the United States.

Russia’s Defense Ministry said that more than 60 Syrian troops were killed in four airstrikes near the city of Deir al-Zour, the Interfax news agency reported.

The troops were surrounded by Islamic State fighters, and the strikes “paved the way for ISIS terrorists to attack” a nearby hilltop, Syria’s military said in a statement reported by the state-run news agency. ISIS is a common name for the Islamic State.

The statement said the alleged strikes were “conclusive evidence that the United States and its allies support ISIS and other terrorist organizations.”