Syrian state TV said there were casualties in what it said was a suspected US missile attack on a major air base in central Syria but the United States denied it had launched any air strikes against the country.
The state broadcaster earlier said explosions were heard at the T-4 airfield near Homs, which is close to the ancient city of Palmyra in central Syria.
According to the Syrian Observatory for Human Rights (OSDH), at least 14 military personnel, including Iranians, were among those killed in the strike that took place shortly before dawn.
A Syrian military source was quoted as saying air defences shot down eight missiles fired at the base, also known as the Tiyas Airbase, where defence analysts say there are large deployments of Russian forces, and where jets fly regular sorties to strike rebel-held areas.
The state broadcaster said there were several dead and wounded in the strike.
The base is in a strategic desert area, where Syria’s main gas fields are located. It had been under the control of Islamic State militants until the Syrian army and its allies regained control last year after heavy Russian military intervention.
“An aggression was perpetrated on T-4 air base in several strikes that is most likely to be an American attack,” state television said in a news flash.
The US Pentagon said it was not conducting air strikes in Syria “at this time,” formally denying the Syrian state television report.
When asked about the explosions, an Israeli spokeswoman declined to comment.
US President Donald Trump said earlier on Sunday there would be a “big price to pay” after medical aid groups reported dozens of civilians, including many children and women, were killed by poison gas in a besieged rebel-held town.
The Syrian state denied government forces had launched any chemical attack. Russia, President Bashar al-Assad’s most powerful ally, called the reports fake.
Various sources have suggested that Israel may be responsible for the attack, which the Russian army claims that two Israeli planes carried out.