By Rory Mulholland, Calais 1:27PM GMT 29 Feb 2016

British woman who is a member of the No Borders activist group, which French officials have accused of encouraging migrants to attack police in the area, was arrested as the operation began

Riot police fired tear gas to push back migrants who set fire to tents and threw stones as bulldozers and demolition teams moved into the Calais "Jungle" camp on Monday.

The clashes came as officials attempted to remove migrants from their shacks after a judge upheld a decision to evict them from the southern part of the squalid camp.

Around 150 to 200 migrants and activists threw stones at police, who later deployed a water cannon.

A British woman who is a member of the No Borders activist group, which French officials have accused of encouraging migrants to attack police in the area, was arrested as the operation began, police said.

Helmeted workers in orange overalls pulled down makeshift structures where migrants had been sleeping in the muddy, rat-infested settlement of wooden shacks and tents that is home to several thousand people.

Police arrived at the camp at dawn and told migrants in the southern section that they had to move out or they would be arrested, aid workers in the camp said.

Lines of police vans gathered on the perimeter of the slum as migrants and refugees were told their only option now was to move.

The operation is the most dramatic step France has ever taken to end Calais’ migrants’ problem, which has festered for years, fuelling support for the the far-Right and causing tension with Britain.

The French government says the removal of up to 1,000 migrants intent onreaching Britain is a “humanitarian operation” and that they are being offered accommodation in containers recently installed nearby or in migrant centres elsewhere in the country.

But many migrants, most of whom have fled war, poverty or persecution in the Middle East or Africa, are reluctant to move because to be allowed access to the containers they have to be fingerprinted.

NGOs also say there are more than 1000 migrants in the southern section of the camp and that many will be left with nowhere to go.

Monday’s operation came after a judge in the city of Lille ruled last Thursday that a partial clearance should go ahead, but that schools, places of worship and other common spaces in the sector should be left intact.

The migrants have grown increasingly desperate since border controls in Calais were reinforced by the British Border Force and French police since the summer. Britain has provided security fencing to prevent migrants from storming the ferry port, the entrance to the Channel Tunnel or the Eurostar rail tracks.

Neighbouring Belgium reintroduced border controls last Tuesday to prevent migrants from the “Jungle” trying their luck from Zeebrugge and other Belgian ports. Belgian police have turned back scores of migrants in the past two days.

Calais 'jungle': Migrants set tents on fire as riot police attempt to evict them - Telegraph