The United Nations human rights chief is calling on the Syrian government and its allies to open humanitarian corridors for civilians to leave areas of fighting.
Michelle Bachelet put out a statement via her spokesman, who said government and Russian forces appear to be targeting civilians and hospitals deliberately.
Nearly 900,000 people have been forced from their homes by fighting in northwest Syria over the last three months.
The Syrian government offensive to capture the last rebel-held areas has created the biggest single civilian displacement since the war began nine years ago.
Half of the three million civilians living in Idlib province have been displaced multiple times in the course of the conflict.
Al Jazeera's Hashem Ahelbarra reports on the crisis in Syria from Cilvegozu in Turkey.