Birds fly over a damaged neighbourhood, in the rebel-controlled area of Maaret al-Numan town in Idlib province, Syria May 23, 2016. REUTERS/Khalil Ashawi/File Photo

BEIRUT (Reuters) - 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.