Conditions for children forced to flee the Syrian government’s ongoing assault on the Idlib region are deteriorating at an alarming rate, humanitarian group Save the Children warned.

Hundreds of thousands of people have been uprooted by the Russian-backed airstrikes forcing an ever-growing number of people to corral into a shrinking pocket of land near the Turkish border.

Humanitarian agency officials say this migration is the biggest single displacement of civilians in the nine-year-old war.

Most of those displaced are facing winter temperatures with no heaters and poor shelters. Families are crowding into flimsy tents in makeshift camps, with very little resources to keep them dry and warm amid harsh winter conditions.

One man staying at a camp in the border city of Azaz said many families have been left without shelter, and children have grown ill because of the cold weather.

Relief workers say at least 10 children have died in recent weeks.

Of Syria’s 17 million people, 5.5 million are living as refugees in the region, mostly in Turkey, and a further six million are uprooted within their own country.