The Mayor of Calais is threatening to close the French port in a row over immigration as she accused Britain of being an “Eldorado” for migrants camped out in her town.
The move would cause gridlock for hundreds of thousands of holidaymakers and road haulage firms.
But Calais mayor Natacha Bouchart said the town was being “taken hostage” by more than 1,000 migrants from the Middle East, Asia and Africa who were desperately trying to get to Britain.
Hundreds of them are daily seeking to clamber onto lorries or into cars and vans to sneak onto a ferry to get across the Channel.
Ms Bouchart raised the prospect of stopping traffic flowing through the French port to stop it being used as a staging-post to the UK.
“I could take the decision to block the port. I could bring pressure to bear,” Ms Bouchart said in Paris after discussing the problem with Interior Minister Bernard Cazeneuve.
The French authorities closed a Red Cross centre at Sangatte, near Calais in 2002 after lengthy negotiations with Britain on how to deal with the growing immigration problem.
But illegal camps keep on getting built by immigrants stranded in Calais but not giving up hope of reaching Britain.
The tented make-shift centres have poor hygiene facilities and have been the scene of violence.
French police have sought to break up the camps where many of the inhabitants sleep under plastic bags and rely on food hand-outs from charities. But hundreds of immigrants are refusing to move on, with more arriving in Calais every week.
Ms Bouchart accepted it would be illegal to block the port.
“But I want to make a strong gesture towards the British,” she added, complaining that UK immigration rules made the country an “Eldorado” for economic migrants.
She is urging the French government to toughen its stance with Britain about how to resolve the crisis.
French ministers are believed to have appealed to the UK government to provide more funding to boost security in Calais.
French police are stationed outside the port entrance as they seek to stop immigrants trying to climb into vehicles heading for the UK.
Earlier this week the French government rejected a plan to open a new Sangatte-style camp in Calais for UK-bound migrants.
Mr Cazeneuve dismissed the call for a base for the migrants.
She said: “I don’t want to create a shelter that would be a hub for migrants.”
Instead “welcome centres” — offering advice on claiming asylum in Britain — may soon go ahead.
