No fewer than 80 Syrian soldiers were killed in a U.S.-led coalition air strike at an army position near Deir al-Zor airport on Saturday.

The Syrian Observatory for Human Rights, a Britain-based monitoring group stated this, citing a source at the airport.

Russian jets had been bombing in the same area at the same time, the group said.

“The source at the airport said the air strike had paved the way for Islamic State fighters to overrun the position at Jebel Tharda,’’ the group said.

It said earlier that only 30 soldiers had been killed, citing the same source.