"These reports are false, the coalition did not strike any Syrian army positions in eastern Syria," Pentagon spokesman Lieutenant Colonel Kone Faulkner said in a statement.

"The coalition's mission is to defeat ISIS in designated parts of Iraq and Syria, and to set conditions for follow-on stability operations. This mission has not changed."

The Britain-based Syrian Observatory for Human Rights, which relies on a broad network of sources across Syria, said the raid had hit army positions south of Albu Kamal, a town on Syria's border with Iraq.

A military source quoted by state news agency SANA said that "some of our military positions between Albu Kamal and Hmeimeh were hit this morning in an aggression by American coalition warplanes."