The Syrian government has said three of its soldiers have been killed in a US-led coalition air strike, but the coalition has denied responsibility.
The foreign ministry said jets fired missiles at an army camp in Deir al-Zour province, which is largely controlled by Islamic State (IS).
The ministry condemned what it called an act of "flagrant aggression".
However, a coalition spokesman insisted that its forces had carried out no strikes in the area near the camp.
Responding to a later report that coalition air strikes may have killed up to 26 civilians in a separate strike in al-Hawl in northern Syria, a spokesman said allegations were taken very "seriously", adding that if the information was deemed "credible", an investigation would be launched and the results released publicly.