UPDATED:

BEIRUT: At least 23 people were killed in Russian air strikes overnight in theSyrian rebel-held city of Idlib, the heaviest bombardment there since a cessation of hostilities was agreed in February, the Syrian Observatory for Human Rights said.

The Observatory said the air strikes targeted a number of positions in the city, one of them next to a hospital. Seven children were among the dead, Observatory Director Rami Abdulrahman said. The toll was likely to rise.

Rescue workers in Idlib worked through the night searching for casualties, finding some survivors including a child under the rubble of destroyed buildings, the Civil Defense in Idlib said on its Facebook page.

Idlib city and the province by the same name is a stronghold of rebel groups including the al Qaeda-linked Nusra Front.

The Russian air force deployed to Syria last year to support President Bashar al-Assad in the war with rebels seeking to end his rule.

Heavy air strikes on Syria's Idlib kill and injure dozens: monitor

BEIRUT: Heavy air strikes in Syria's rebel-held city of Idlib on Monday evening killed and injured more than 150 people, the Syrian Observatory for Human Rights said.

The war monitor said it believed the planes were Russian.

At least seven strikes hit the western Syrian city, it added. Some struck the area where the national hospital is located, the war monitor said, noting that it did not think the strikes hit the hospital itself.