Moscow: Russia's Foreign Ministry said on Sunday the air strikes by a US-led coalition on Syrian army forces threatened the implementation of a US ceasefire plan for Syria and urged Washington to thoroughly investigate the accident.
The Russian Defence Ministry said on Saturday that US jets had killed more than 60 Syrian soldiers in four air strikes by two F-16s and two A-10s coming from the direction of Iraq.
The Syrian Observatory for Human Rights, a British-based monitoring group with contacts across Syria, cited a military source at Deir al-Zor airport as saying at least 90 Syrian soldiers had been killed.
Russia's Foreign Ministry said in a strongly worded statement that the strikes were "on the boundary between criminal negligence and direct connivance with Islamic State terrorists".
It said the incident was a result of Washington's "stubborn refusal" to cooperate with Moscow in fighting Islamic State, the Nusra Front - now renamed Jabhat Fatah al Sham - and "other terrorist groups".
