An air strike on an army camp has killed three soldiers, the Syrian government says, blaming the US-led coalition for the attack.
It said warplanes fired missiles at the camp in Deir al-Zour province, which is largely controlled by the jihadist group Islamic State (IS).
The ministry condemned what it called an act of “flagrant aggression”.
However, a coalition spokesman denied that its forces had carried out any strikes in the area.
The coalition has been targeting IS militants in Syria since September 2014, and does not co-ordinate with the authorities in Damascus.
Last week, the UK decided to participate in the air strikes in Syria, extending its existing bombing campaign against IS in Iraq.
The Syrian foreign ministry said four coalition warplanes fired nine missiles at the camp in Deir al-Zour province on Sunday evening, killing three soldiers and wounding 13 others.
Three armoured vehicles, four military vehicles, heavy machine-guns and an arms and ammunition depot were destroyed, it added.
The ministry did not say which camp was hit, but the Syrian Observatory for Human Rights earlier reported that coalition jets had bombed part of the Saeqa camp, near the town of Ayyash in western Deir al-Zour.
The UK-based monitoring group put the death toll at four.
“The Syrian Arab Republic strongly condemns this flagrant aggression by the US-led coalition forces, which blatantly violates the objectives of the UN Charter,” the foreign ministry warned.
The ministry called on the UN Security Council to “take urgent measures to prevent such aggressions from occurring again”.
It added that such “aggression hinders the efforts to fight terrorism, and proves that the US-led coalition lacks seriousness and credibility to effectively fight terrorism”.
However, coalition spokesman Col Steve Warren denied it was responsible.
“We’ve seen those Syrian reports but we did not conduct any strikes in that part of Deir al-Zour yesterday. So we see no evidence,” he told the AFP news agency.
Col Warren said the coalition’s only strikes in Deir al-Zour were some 55km (34 miles) away from the area where the Syrian soldiers were reportedly killed.
A separate strike believed to have been carried out by the coalition in the nearby city of Deir al-Zour overnight killed a woman and two of her children, the Syrian Observatory said.
IS controls most of Deir al-Zour province, including almost all of its capital.
The province links the group’s headquarters in Raqqa with territory controlled by the group in western Iraq, and its oilfields are also a major source of revenue for IS.