Moscow is one of Syrian President Bashar al-Assad's key backers, providing him with military, political and economic support in the country's 12-year civil war.

"On December 25 at 10:00 pm (0700 GMT) Russian warplanes targeted civilian houses" on the outskirts of the town of Armanaz, in Idlib province, said Abdel Halim Shehab of the White Helmets voluntary search-and-rescue group.

Members of the White Helmets, which operates in rebel-held zones of northern Syria, pulled the victims from under the rubble of their house, he said.

"The victims were from the same family of six: five of them were killed and a child survived," he said, identifying the dead as the father, mother and three of their children.

The Syrian Observatory for Human Rights, a war monitor with a network of sources across the war-torn country, also said Russia carried out the strikes.

The Britain-based organisation reported the same toll of five dead and said the family's house was located on farmland near Armanaz.

A brutal Syrian government crackdown on Arab Spring-inspired protests that erupted in 2011 spiralled into a devastating war involving foreign armies, militias and jihadists.

More than half a million people have been killed in the conflict.

Russia's intervention in the war since 2015 has helped forces loyal to Assad claw back much of the territory they lost to rebels early in the conflict.

Hayat Tahrir al-Sham, a jihadist group led by Al-Qaeda's former Syria branch, controls swathes of Idlib province and parts of neighbouring Aleppo, Hama and Latakia provinces.

The HTS is considered a terrorist organisation by Syria, the United States and the European Union. It regularly clashes with Syrian and allied Russian forces.

On Sunday, Syria's defence ministry said its forces had shot down seven drones launched by "terrorist organisations" in Hama and Aleppo provinces.

Since 2020, a ceasefire deal brokered by Russia and rebel-backer Turkey has largely held in Syria's northwest, despite periodic clashes.