Russian air strikes in Syria's Idlib on Monday killed 27 civilians, said a United Kingdom-based monitor.
The air strike was in northwest Syria's mainly jihadist-controlled province of Idlib, marking the highest civilian death toll ever since the region was designated in May as one of Syria's de-escalated zones, said the Syrian Observatory for Human Rights.
Observatory chief Rami Abdel Rahman told news agency, AFP, "The air raids struck several locations and villages in the Jisr al-Shughur area of the province bordering Turkey, leaving 27 dead among civilians, 10 of them children".
Idlib province has been the target of heavy air strikes for the past two weeks by the regime and Russian allies after several months of calm.
The neighbouring Hama province in Syria, following a jihadist assault, has also been covered by the de-escalation accord for Syria's war costing more than 330,000 lives since 2011.