US-led coalition airstrike 'mistakenly' hits Syrian military base

American officials said the US-led coalition fighting the Islamic State [IS] group in Syria may have hit Syrian military positions.

"Coalition forces believed they were striking a Daesh fighting position," a Pentagon statement said, using an Arabic acronym for the IS group. 

"The coalition air strike was halted immediately when coalition officials were informed by Russian officials that it was possible the personnel and vehicles targeted were part of the Syrian military."

The strike marks the first known time the US hit Syrian government forces since the start of the five-year conflict.

"Warplanes from the American coalition hit one of the Syrian army's positions... near the Deir Ezzor airport," a statement carried by Syrian state media said.

"This is a dangerous and bold attack against the Syrian state and army, and clear evidence that the United States and its allies support the terrorist group Daesh," the statement added, using an Arabic acronym for IS.

Syrian regime ally Russia said 62 Syrian soldiers were killed and at least 100 more wounded in strikes by "warplanes from the international anti-jihadist coalition".

Russian Defence Ministry spokesman Major General Igor Konashenkov said the airstrike was conducted by two F-16s and two A-10s. He did not identify the plane's country affliation, but said they were part of the international coalition.

Konashenkov said that if the coalition attack was launched by mistake, the reason for it was a "stubborn reluctance by the American side to coordinate its action against terrorist groups in Syria with Russia."

The Syrian regime has been fighting off a fierce offensive by the Islamic State [IS] group on the Deir Ezzor military airport since last year.

It said the raids had allowed IS to advance on Syrian troops in the area.

Under a fragile truce deal negotiated by the United States and Russia, fighting in Syria is to halt on all fronts across the country except those held by IS.

The deal came into force on Monday. If it holds for a week, Moscow and Washington are to begin unprecedented joint operations against jihadist groups in Syria.  

The US-led coalition has been carrying out raids against IS for two years in both Syria and Iraq.