French farmers and truckers launched a joint operation Monday to block off main routes in and out of Calais to call for the closure of the vast "Jungle" migrant camp there.

Under a light rain, around 70 trucks began a "go-slow" on the main A16 motorway -- the main artery for freight and passengers heading for Britain either via the Channel Tunnel or the Calais port.

Farmers were expected to join the demonstration later on their tractors and organisers hoped for up to 500 people to join a "human chain" protest in the main stadium later Monday.

"We've had no answers, so we're blocking things up," said Frederic Van Gansbeke, who represents businesses and shop-owners in Calais.

Nicolas Lotin, who runs a logistics company in nearby Boulogne-sur-Mer said: "Every day, we have to wonder whether our working day will be ruined, whether a migrant will sneak under the truck's canvas."

"If the goods are damaged, they have to be immediately transported back to the home depot," he said.

Migrants from the "Jungle" often create their own road blocks to slow trucks heading for Britain, seen as an El Dorado. By slowing the vehicles, they hope to stow away aboard.

Interior Minister Bernard Cazneneuve vowed last week to close the "Jungle" camp "as rapidly as possible."

France has made repeated efforts to shut down the camp of tents and temporary shelters, which authorities say is currently home to nearly 7,000 migrants following a surge of new arrivals in recent months.

Charities helping the migrants in the camp say the real figure is as high as 10,000.