LONDON - At least 22 civilians have been killed in 48 hours of heavy air strikes by Syria's regime and its ally Russia in northwestern Syria, a monitor said Thursday.
The strikes hit areas in the provinces of Idlib and Hama, where an internationally agreed truce zone is meant to be in place, and come in response to an offensive launched Tuesday by jihadists.
Idlib, along with parts of neighbouring Hama and Latakia provinces, forms one of four so-called de-escalation zones agreed last May by regime allies Russia and Iran and rebel backer Turkey.
The agreement has brought relative calm to the regions involved, but the Syrian Observatory for Human Rights has reported dozens of raids on Hama and Idlib since Tuesday, when jihadists began attacking government positions.
"The Russian and regime aircraft are practically not leaving the sky over Idlib and Hama," the Britain-based monitor said.
On Thursday, at least four people including a father and his two daughters were killed in Russian raids on the town of Khan Sheikun in Idlib, the monitor said, raising the civilian death toll in 48 hours of strikes to 22.
Dozens more have been injured, according to the Observatory, which relies on a network of sources inside Syria and says it determines whose planes carry out raids according to type, location, flight patterns and munitions used.
Jihadist factions led by a former Al-Qaeda affiliate, which are not included in the de-escalation deal, launched a fierce assault on Tuesday on a string of government-held villages along the border between Idlib and Hama.
The fighting erupted just days after Iran, Russia and Turkey announced they would jointly police the safe zone in Idlib, Hama, and Latakia provinces.
Russia has already deployed military police to the other three safe zones -- Eastern Ghouta near Damascus, parts of the south and some areas of the central province of Homs.
The de-escalation agreement excludes the jihadists of the Islamic State group and Hayat Tahrir al-Sham, an alliance dominated by Al-Qaeda's former Syrian affiliate.
More than 330,000 people have been killed in Syria since the conflict began with anti-government protests in March 2011.