'Over 150 killed' in week of deadly Idlib bombing campaign
Russia's defence ministry says it is targeting hard-line Islamist militants and denies accusations that it has struck civilian infrastructure and medical centres to force rebels into local truces.
Thousands of civilians have fled from towns such as Jisr al Shqour and Jabal al Zawya to rural areas less exposed to daily bombing, aid workers say.
The United Nations on Thursday condemned the airstrikes on five hospitals and humanitarian warehouses in Idlib, calling for a system to protect civilians and medical facilities near armed groups.
"We urgently need a workable and respected system of notification for these protected localities that armed actors will respect," Jan Egeland, the UN's humanitarian adviser on Syria, told reporters.
He said it was not clear who carried out the attacks, but said it was part of a trend to attack "humanitarian lifelines" including hospitals, ambulances and health workers.
The Russian and Syrian bombing campaign comes shortly after Syrian regime allies Russia and Iran agreed with opposition backer Turkey to jointly police a "de-escalation" zone in Syria's Idlib province.
Turkish President Recep Tayyip Erdogan has said that Turkish troops will deploy inside Syria's northern Idlib region as part of the agreement, while Russia would maintain security outside the province.
The Idlib zone is the fourth such area to be agreed among Turkey, Russia, and Iran, and was widely expected to be the most complex zone to establish.
Much of it is held by Hayat Tahrir al-Sham (HTS), an alliance of fighters dominated by Al-Qaeda's former Syrian affiliate.