Syira's ambassador to the United Nations has criticized the United Stated for attacking the Syrian army. Speaking at a summit of the Non-Aligned Movement in Venezuela, he said the air strikes prove a "link" between the US and ISIL.

"US troops committed a new hostile action against my country yesterday when five war planes attacked positions of the Syrian army, leading to deaths and injuries within the Syrian army," said Bashar Ja'afari, Syira's UN ambassador.

"We have to note that ISIL, immediately after this attack, attacked the area which had been attacked by US troops hours before. This proves clearly the link between US troops and ISIL, and the Americans said the attack was just an error -- this is clearly a lie."

Russia's defense ministry said over 60 Syrian soldiers were killed by US-led air strikes on the outskirts of the eastern city of Deir el-Zour.

The US military said it had launched attacks against what it believed to be ISIL positions in northeast Syria. The missions were halted after Russia informed the US that Syrian military personnel and vehicles had been hit. The US has since relayed its "regrets".

Russia's Foreign Ministry says the incident endangers the US-Russia ceasefire plan for Syria. Moscow has urged Washington to conduct a thorough investigation of the incident.