More than 1,200 police and officials in France have begun an operation to clear the ‘Jungle’ migrant camp in Calais.
Authorities say some 7,000 people live in the camp in squalid conditions.
Dozens of migrants began queuing early at reception points where they will be processed and bussed to refugee centres across France.
But there is concern that some migrants will refuse to go because they still want to get to Britain, and there have been some clashes over the weekend.
The UK has begun to accept some of the estimated 1,300 unaccompanied children from the camp.
The first group without family ties to the UK has arrived in Britain under the ‘Dubs amendment’ rules, which grant refuge to the most vulnerable.
Charities are helping the French authorities to process minors that remain in the camp, by conducting interviews and establishing who should also be transferred to the UK.
Amid concerns for their safety, children will be taken to the camp's converted shipping containers while the rest of the Jungle is dismantled, according to the French interior ministry.
The migrants who currently live in the containers - which were being used as temporary accommodation instead of makeshift tents - will be evacuated to make room for them.
About 10,000 leaflets were handed out by the French authorities, informing people about the plans for the clearance.
The BBC's Simon Jones, at the camp in Calais, says queuing for the reception points began four hours before they were to start the processing operation.
He said most people seemed in good spirits despite the slightly chaotic scenes.
The migrants willing to leave will be put on some 60 coaches for other parts of France and be given the opportunity to claim asylum.
There are 7,500 beds available in centres across France for the Calais migrants.
From Tuesday, heavy machinery will be sent to clear the tents and shelters that have been left behind.
The whole operation is expected to take three days.
The French interior ministry said it ‘does not want to use force but if there are migrants who refuse to leave, or NGOs who cause trouble, the police might be forced to intervene’.
One Afghan migrant at the camp, Karhazi, told the AFP news agency: ‘They'll have to force us to leave. We want to go to Britain.’
The Jungle has played host to scenes of both squalor and of violence, as migrants, mainly from Africa and the Middle East, attempt to board lorries bound for the UK, clashing with drivers and police in the process.
A UK-funded wall 1km (0.6 miles) long is being built along the main road to the port in an attempt to deter would-be stowaways. The UK government has not confirmed the cost, but it is reported to have contributed about £1.9m (€2.2m).
Work on the wall, which began last month, is due to be finished by the end of the year.
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