A monitoring group says at least 60 people have died in an attack in Syria’s northwestern Idlib Province.
The UK-based Syrian Observatory for Human rights said dozens were also wounded in the strike, which it said targeted the province on Tuesday.
The pro-opposition body cited “medical sources” as saying that victims displayed symptoms of asphyxiation, which they said could mean that chemical agents were used in the attack.
Those claims and the report about the alleged attack could not be independently verified.
‘Never in the past and never in the future’
Later on Tuesday, a Syrian military source said the Syrian army “does not [use] and has not” used chemical weapons, “not in the past and not in the future.”
Meanwhile, a senior Syrian security source was quoted by AFP as saying that allegations about Syria's government being behind a chemical attack in Syria’s northwestern Idlib Province were are "false."
"This is a false accusation," the source said, adding that opposition forces were attempting to "achieve in the media what they could not achieve on the ground."
Separately, a Syrian member of parliament, Sharif Shahada, said he believed a chemical arms depot set up and held by the militants in the area may have exploded in the incident. He said the Syrian government was not in possession of such weapons.
Shahada also accused Turkey of having supplied militants in Syria with chemical arms.
The United States and its allies have in the past accused the Syrian military of conducting chemical attacks. This is while Syria turned its entire chemical arsenal over to international monitors under a deal negotiated by Russia and the United States back in 2013.
The Syrian stockpiles of chemical weapons were surrendered in a joint mission comprising representatives of the United Nations (UN) and the Organization for the Prohibition of Chemical Weapons (OPCW) in 2014.
That same year, Daesh started a campaign of deadly terror in the Arab country. Damascus has continuously warned about the deployment of chemical arms by Daesh and its fellow Takfiri outfits against civilian targets.
The Syrian government and the anti-Damascus militants reached a deal last Wednesday enabling the evacuation of civilians from the Shia-populated towns of al-Foua and Kefraya in Idlib, which have been under militant siege, in exchange for the evacuation of militants and their families from the Sunni-majority towns of Zabadani and Madaya near Syria’s border with Lebanon.
But the Observatory said on Tuesday that those evacuations had been delayed over reservations by the residents in the four towns and other issues. It said the evacuations had been delayed likely to Thursday or Sunday.
A ceasefire has also been largely holding over the entire country, but it excludes internationally-recognized terrorist groups.