Calls have been made to renegotiate a border deal which keeps border checks - and many migrants - on the French side of the Channel after the UK's Brexit vote.
The Touquet agreement between France and the UK has been called into question following Britain's vote to leave the European Union.
Prior to the referendum, a French government minister had warned a vote for Brexit could see migrant camps being moved from Calais to Britain.
Finance minister Emmanuel Macron said in February that the treaty, which was signed in 2003, could be scuppered, telling reporters: "The day this relationship unravels, migrants will no longer be in Calais."
Now, after 51.9% of people voted for the UK to leave the bloc of 28 nations, the mayor of Calais is among those pressing for a renegotiation of the treaty.
Natacha Bouchart told French broadcaster BFM TV: "The British must take on the consequences of their choice.
"We are in a strong position to push, to press this request for a review and we are asking the President to bring his weight (to the issue).
"We must put everything on the table and there must be an element of division, of sharing."
This echoed calls from Xavier Bertrand, the centre-right president of the Hauts-de-France region, who tweeted: "The English wanted to take back their freedom, they must take back their border."