There have been 200 air strikes on opposition-held territory in northern Syria in the last three days, mainly targeting civilians, the US has said.
In one of the latest raids, 11 civilians were killed in reported Russian air strikes near a bakery and a clinic in the town of Ariha.
Russia denied its forces were involved.Fighting in Idlib, the last stronghold of the opposition to President Bashar al-Assad, has intensified in recent weeks as the Syrian army pressed on with an offensive.
On Wednesday, soldiers captured the strategically important town of Maarat al-Numan, which straddles a highway linking the capital Damascus with Aleppo. Now the soldiers have pushed further north, towards Ariha and Saraqeb.
“Every single day there is bombing. If a day passes without us hearing any missiles, any aircraft, any warplanes, we are afraid that they are preparing for something bigger than this,” an English teacher in the east of the opposition enclave said.