Aerial photos show how the migrant camp at Calais, known as "the Jungle", has spread across the wasteland near the ferry terminal as the migrant crisis has intensified.
The number of people crammed into the makeshift camp is now estimated to be between 4,000 and 6,000 men, women and children.
There were around 2,500 people at the start of June.
"We are on the brink of collapse," Jean-Francois Corty, head of the French division of Medecins du Monde (Doctors of the World) told the AFP News agency.
"The social welfare system is inadequate and so are the delays to process asylum applications," he said.
"It is unacceptable for a country, the sixth biggest world economic power, to support that."
See how the makeshift camp has grown by moving the slider below
Aerial image of camp in July 2015
Aerial image of camp in October 2015
French officials have said women and children at the camp will be given heated tents by the end of the week, while they plan to double capacity at a centre that currently has space for 200.
The authorities also plan to increase the number of police officers deployed to the area to help manage security.
Most of the people at the camp have fled conflict and poverty in Africa, the Middle East and Afghanistan and are trying to seek refuge across the Channel in the UK.
Some people have tried to hide on lorries, while others have attempted to board trains heading to England via the Channel Tunnel - sometimes with fatal consequences.
The International Organisation for Migration (IOM) says more than 650,000 migrants have reached Europe this year.
A note on terminology: The BBC uses the term migrant to refer to all people on the move who have yet to complete the legal process of claiming asylum. This group includes people fleeing war-torn countries such as Syria, who are likely to be granted refugee status, as well as people who are seeking jobs and better lives, who governments are likely to rule are economic migrants.