At least 35 Syrian soldiers were killed overnight when an army cargo plane crashed in bad weather in the northwest of the country, a monitor said on Sunday.
The Syrian Observatory for Human Rights said the plane crashed after hitting electricity lines in heavy fog in Idlib province, a claim echoed by Syrian state media.
But Syria's al-Qaida affiliate al-Nusra Front claimed on Twitter that it had shot down the aircraft.
Syrian state media reported the crash without giving a death toll.
"A medium-sized cargo plane crashed last night while landing at the Abu al-Duhur military airport because of bad weather conditions and heavy fog, killing the crew on board," state news agency SANA said.
It gave no further details on the incident.
The Observatory said the planes was carrying troops as well as military equipment and ammunition.