Australian aircraft were involved in a US-led coalition operation which killed dozens of Syrian soldiers who were apparently mistaken for Islamic State fighters, the Defence Department has confirmed.

Key points: Dozens of Syrian soldiers dead in US-led strike

Dozens of Syrian soldiers dead in US-led strike Defence Department says Australian jets were involved but would never intentionally target Syrian military

Defence Department says Australian jets were involved but would never intentionally target Syrian military UN Security Council holds emergency meeting at Russia's request, US criticises "grandstanding"

Between 62 and 83 Syrian soldiers who had been fighting IS militants were reportedly killed in the air strikes around the Deir al-Zor military airport in Syria's east.

"Australian aircraft were among a number of international aircraft taking part in this Coalition operation," the Defence Department said in a statement.

"Australia would never intentionally target a known Syrian military unit or actively support Daesh (IS). Defence offers its condolences to the families of any Syrian personnel killed or wounded in this incident."

The Russian military earlier said two F-16s and two A-10 jets that flew into Syrian airspace from neighbouring Iraq carried out the actual attack. Neither type is listed as being in operation with the RAAF.

The strikes came less than a week into a fragile ceasefire aimed at stopping the bloodshed in Syria's five-year civil war, as Russia accused what it termed "moderate rebels" of causing the truce to fail.

'Russia needs to stop cheap point-scoring': US

US-led aircraft killed dozens of Syrian troops in the attack ( Reuters )

The US military and Australia's Defence Department said the attack was called off after Russia informed the coalition that Syrian military personnel and vehicles may have been hit.

Pentagon press secretary Peter Cook said in an emailed statement that Russian officials did not voice concerns earlier on Saturday when informed that coalition aircraft would be operating in the strike area.

The 15-member United Nations Security Council met after Russia demanded an emergency session to discuss the incident and accused the US-led coalition of jeopardising the Syria deal and helping Islamic State.

The US ambassador to the United Nations, Samantha Power, chastised Russia for the move.

"Russia really needs to stop the cheap point-scoring and the grandstanding and the stunts and focus on what matters, which is implementation of something we negotiated in good faith with them," Ms Power said.

When asked if the incident spelled the end of the Syria deal between Moscow and Washington, Russia's UN ambassador Vitaly Churkin said: "This is a very big question mark."

"I would be very interested to see how Washington is going to react. If what Ambassador Power has done today (Sunday) is any indication of their possible reaction then we are in serious trouble," Mr Churkin said.

Russia says attack helped Islamic State

Russia said the attacks, which allowed Islamic State fighters to briefly overrun a Syrian army position near Deir al-Zor, were evidence that the US was helping the jihadist militants.

"We are reaching a really terrifying conclusion for the whole world —that the White House is defending Islamic State. Now there can be no doubts about that," the RIA Novosti news agency quoted Russian Foreign Ministry spokeswoman Maria Zakharova as saying.

"Warplanes from the international anti-jihadist coalition carried out four air strikes today (Sunday) against Syrian forces surrounded by IS in the Deir Ezzor air base," a Russian army statement said.

"Sixty-two Syrian soldiers were killed and a hundred others were injured in these strikes.

The Syrian Observatory for Human Rights monitoring group gave a toll of 83 soldiers killed, and said the strikes were US-led coalition raids.

Military airport has been scene of fierce fighting



The Russian military said A-10 jets were among those which carried out the attack. ( Reuters: Ints Kalnins )

Coordination between the US, which backs some Syrian rebels, and the Russian military, which backs the Syrian government, is a controversial issue.

Russia has long insisted on it and, if the ceasefire brokered by the two nations holds, the two nations are supposed to start coordinating attacks on Islamic State.

Russia says the incident is evidence the US has stubbornly refused to coordinate so far.

But the US says the coalition did inform Russia of the forthcoming strike.

Syria's army has been fighting off a fierce Islamic State offensive around the Deir al-Zor airport since last year.

The IS-linked Amaq news agency said coalition strikes also hit Islamic State positions around the airport, while there were also reports of Russian planes bombing Islamic State targets..

Situation worsening, says Russian general

Russian military officials meanwhile lashed out at both the United States and mainstream rebels over the ceasefire struck last week in Geneva.

"The situation in Syria is worsening," said Russian General Vladimir Savchenko in a briefing.

Under the US-Russia deal, if the truce lasts seven days and humanitarian access is granted, Moscow and Washington are to work together to target jihadists including IS.

"Russia is exerting all possible effort to restrain (Syrian) government troops from returning fire," Senior Army General Viktor Poznikhir said.

"If the American side does not take the necessary measures to carry out its obligations... a breakdown of the ceasefire will be on the United States."

In a statement, the Russian defence ministry accused what it termed "moderate rebels" of causing the ceasefire to fail.