US-led coalition air strikes reportedly hit Syrian military personnel and caused casualties on Saturday after mistaking them for Islamic State targets.
The incident endangers a US-Russian brokered ceasefire and prompting an emergency UN Security Council meeting as tensions escalated between Moscow and Washington.
The Syrian Observatory for Human Rights monitoring group said least 83 soldiers were killed and more than 120 were wounded in the raids, which the US military said, took place south of Dayr Az Zawr in Syria.
The Russian defence ministry has put the number of those killed at 62, with over 100 wounded.
The US central command, which has charge of military operation in the region, said an airstrike against IS targets, which was being tracked for a “significant amount of time” by the coalition, was cut short after Russian officials said the targets may have belonged to the Syrian military instead.
“It is not uncommon for the Coalition Air Operations Center to confer with Russian officials as a professional courtesy and to deconflict coalition and Russian aircraft, although such contact is not required by the current US memorandum of understanding on safety of flight,” US said in a statement.
A senior Obama administration official said in an emailed statement the US had relayed its “regret” through the Russian government for what it described as the unintentional loss of life of Syrian forces in the strike.
It went on to say that “coalition forces would not intentionally strike a known Syrian military unit”.
“The coalition will review this strike and the circumstances surrounding it to see if any lessons can be learned.”
The 15-member Security Council met on Saturday night after Russia demanded an emergency session to discuss the incident and accused the United States of jeopardising the Syria deal.
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,” Power told reporters before the meeting.
She said the United States was investigating the air strikes and “if we determine that we did indeed strike Syrian military personnel, that was not our intention and we of course regret the loss of life.”
Moscow cited the strikes, which allowed Islamic State fighters to briefly overrun a Syrian army position near Deir al-Zor airport, as evidence that the United States was helping the 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 spokesperson Maria Zakharova as saying.
She said the strikes threatened to undermine the ceasefire in Syria brokered by Russia, which has been aiding Syria’s President Bashar al-Assad in the civil war, and the United States, which has backed some rebel groups.
The ceasefire, which took effect on Monday, is the most significant peacemaking effort in Syria for months, but has been undermined by repeated accusations of violations on both sides and by a failure to bring humanitarian aid to besieged areas.
Apart from the US and Russian involvement, Assad is supported by Iran and Arab Shia militias, while Sunni rebels seeking to unseat him are backed by Turkey and Gulf Arab states.
In its sixth year, the conflict has cost hundreds of thousands of lives, displaced half of Syria’s pre-war population, prompted a refugee crisis in the Middle East and Europe and inspired a wave of jihadist attacks across the world.
(With inputs from Reuters)