Prime Minister Malcolm Turnbull has expressed regret about a coalition airstrike in Syria that killed Syrian government troops in an operation involving Australian fighter jets.

Mr Turnbull said Australian jets were part of the sortie that resulted in the airstrike that killed as many as 83 Syrian soldiers mistaken for Islamic State (IS) fighters.

“As soon as the coalition were advised that there were Syrian government personnel that had been affected by the strike, the operation was discontinued,” he said.

“Australian aircraft were involved as part of the coalition, we regret the loss of life and injury to any Syrian personnel affected.”

The Defence Department said in a statement on Sunday: “While Syria remains a dynamic and complex operating environment, Australia would never intentionally target a known Syrian military unit or actively support Daesh (also known as IS),” the Defence Department said.

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.

Mr Turnbull said Australia’s rules of engagement are to target Islamic State but it is a very complex environment.

He admitted it remains to be seen whether the Syrian ceasefire will be put in jeopardy.

The Syrian Observatory for Human Rights monitoring group has put the death toll at 90 soldiers.

The Russian military earlier said two F-16 and two A-10 jets that flew into Syrian airspace from neighbouring Iraq carried out the actual attack.

Neither aircraft is listed as being in operation with the RAAF.

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.

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.

Syrian soldiers walk through the government-held side of Aleppo. Photo: AP

‘Russia needs to stop cheap point-scoring’: US

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

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 is any indication of their possible reaction then we are in serious trouble,” Mr Churkin said.

Moscow claimed the strikes, which allowed Islamic State fighters to briefly overrun a Syrian army position near Deir al-Zor airport, were evidence that the United States was helping the jihadist militants.

“We are reaching a really terrifying conclusion for the whole world: That the White House is defending Islamic State,” the RIA Novosti news agency quoted Russian Foreign Ministry spokeswoman Maria Zakharova as saying.

An RAAF Super Hornet in the sky over Iraq. The RAAF gave no details of the planes involved in the operation. Photo: Australian Defence Force: Sgt Pete

Military airport has been scene of fierce fighting

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.

F-16 jets were involved in the attack. Photo: Getty

The ceasefire has so far lasted five days.

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.

– with ABC, AAP