President Francois Hollande said on Monday that France will completely shut down "the Jungle" migrant camp in Calais and called on London to help deal with the plight of thousands of people whose dream is ultimately to get to Britain.
"The situation is unacceptable and everyone here knows it," Hollande said on a visit to the northern port city where as many as 10,000 migrants from war-torn countries such as Syria, Iraq and Afghanistan live in squalour.
"We must dismantle the camp completely and definitively," he said.
France plans to relocate the migrants in small groups around the country but right-wing opponents of the Socialist leader are raising the heat ahead of the election in April, accusing him of mismanaging a problem that is ultimately a British one.
The migrants want to enter Britain, but the government in London argues that migrants seeking asylum need to do so under European Union law in the country where they enter.
Immigration was one of the main drivers of Britain's vote this year to leave the EU. It is also likely to be major factor in France's presidential election.
If France stopped trying to prevent migrants from entering Britain, Britain would ultimately find tself obliged to deal with the matter when asylum-seekers land on its shores a short distance by ferry or subsea train from France's Calais coast.
Hollande bluntly reminded Britain of that, saying that he expected London to fully honour agreements on managing a flow of migrants.
"I also want to restate my determination that the British authorities play their part in the humanitarian effort that France is undertaking and that they continue to do that in the future," Hollande said.
London and Paris have struck agreements on issues such as the recently begun construction of a giant wall on the approach road to Calais port in an attempt to try to stop migrants who attempt daily to board cargo trucks bound for Britain.