Refugee charity Care 4 Calais has released images of migrant children sleeping without shelter after an operation to demolish the "Jungle" refugee camp began on Monday.
Some 5,596 people have been evacuated from the camp, and plans are underway to move migrants on to resettlement centres across France.
Fires raged across the camp on Wednesday as French authorities demolished the site.
Charities warned that the fires destroyed safe spaces for children, meaning 40 unaccompanied minors were forced to sleep in a mosque.
Local police subsequently arrested four migrants in connection with starting the fires.
Teenagers gathered at a makeshift church in the Calais 'jungle' just days after authorities declared the operation to clear the camp over.
Those still left after the demolishing of the 'Jungle' camp were seen wrapped in blankets as they prepared to sleep rough.
The UK's French ambassador, Sylvie Bermann said the destruction of the Calais 'Jungle' will encourage refugees to seek asylum in France.