“Air strikes killed 22 people in the north western Syrian province of Idlib on Friday”, the Syrian Observatory for Human Rights said, on the last day of a three day ceasefire announced by the Syrian army.

The air strikes hit the town of Darkush, near the Turkish border, in western Idlib province. Idlib province and city are strongholds of rebel groups including the al Qaeda-linked Nusra Front.

“The death toll, which included nine women, is likely to rise due the number of severely injured people”, the Observatory said.

A 72-hour ceasefire was announced by the Syrian army on Wednesday, but rebels and the Observatory said there has been little let up in the violence.

On Thursday, Syrian government forces took a step towards completely encircling rebel-held parts of Aleppo, capturing ground overlooking the only road into the opposition half of the city and effectively putting those areas under siege.

Russia deployed warplanes to Syria last year to support President Bashar al-Assad against rebels seeking to end his rule, and have supported Syrian government forces in a separate fight against Islamic State further east.

Fighting in Syria’s five-year civil war has intensified since a February ceasefire deal, which took hold in the west of the country but excluded the al Qaeda-affiliated Nusra Front and Islamic State, quickly began to unravel.