(CNN) At least 44 people were killed in airstrikes on a village in the rebel-held Syrian province of Idlib, a local activist media group and a UK-based monitor said Friday, describing it as one of the deadliest attacks in the province this year.

The Idlib Media Center said Russian airstrikes hit homes in the village of Zardana on Thursday. The UK-based Syrian Observatory for Human Rights said the "aircrafts that conducted the airstrikes are presumed to be Russian."

Russia's Defense Ministry denied involvement. Reports about "the alleged strikes carried out by Russian aircraft in the evening of June 7 near the settlement of Zardana in the Idlib province are untrue," the ministry said Friday in a statement carried by state media.

Russia has provided military backing to the forces of Syrian President Bashar al-Assad since 2015.

The northern province of Idlib is meant to be one of the so-called "de-escalation zones" agreed to in a deal struck by Russia, Turkey and Iran last year. In theory, such zones, also referred to as non-conflict or safe zones, are meant to be areas where civilians can live without being targeted by any party in Syria's conflict.

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