French riot squad officers have returned to the Calais migrant camp known as the Jungle as a third successive day of clearing the slum of makeshift homes got under way.
Hundreds of CRS officers armed with tear gas, batons and riot shields surrounded the squalid site where about 4000 people live, with many intent on reaching the UK.
Migrants and refugees who have fled war, poverty and persecution looked on as bulldozers dismantled shacks and piled belongings into containers.
In an effort to halt the slow tear-down, some people sat on top of the flimsy homes as banks of CRS officers watched the crowds within the camp's southern section.
Local government official Vincent Berton said the operation to clear the southern section would last three weeks.
And he said the overall aim was to halve the population size of the sprawling site to around 2000.
He said: "On Monday morning we were surprised by the little number of people here.
"We are trying not to shift the problem. We are very focused. We are trying for a better solution especially for the children."
French authorities want to relocate people from the rat-infested site to heated containers nearby or to centres around France where they can apply for asylum. State authorities have said up to 1000 people will be affected.
But aid workers say the figure is likely to be much higher. Help Refugees said its own analysis revealed there were 3455 people living in the affected area.
Save The Children said nearly 400 unaccompanied children who have fled war, poverty and persecution live at the site.
Campaigners had called for a postponement to remove people from the slum, saying there was not enough new accommodation for people to move to.
Calais has lived with migrants in its midst for years, but the current camp on the city's edge sprang up around a day centre opened last April by the state - and has grown explosively.
The estimated 4000 people now camped at the Jungle are significantly fewer than the 6000 that were there in December.
Repeated bids to cross the Channel to Britain have been made by migrants, prompting an Anglo-French operation to bolster security around the ports, including the erection of razor-topped fences.
Some have criticised the decision to send in demolition teams. But British hauliers welcomed last week's court judgment.
The Freight Transport Association said mass disruption caused by migrants cost the UK freight industry an estimated STG750,000 a day last year.
FTA officials said a solution needed to be found to protect the STG89 billion ($A173.19 billion) of UK trade which passes through cross-Channel ports annually.
Many truckers have reported facing intimidation and violence from migrants attempting to climb into their vehicles for passage to Britain.
