France could end UK border controls in Calais and allow migrants to cross the Channel unchecked if the UK leaves the EU, France’s finance minister has said.
Emmanuel Macron told the Financial Times his country could also limit access to the single market and try to tempt London’s bankers to relocate.
His comments come as David Cameron and Francois Hollande prepare for security and migration talks in France.
Pro-exit London Mayor Boris Johnson urged voters to “ignore scaremongers”.
British voters will be asked whether the UK should remain in the European Union or leave, in a referendum on Thursday 23 June.
Mr Macron told the FT that if the vote were in favour of a so-called Brexit, it could bring to an end the agreement between the two countries that allows the UK to conduct border controls on the French side of the Channel.
There are currently believed to be about 4,000 migrants amassed in Calais, hoping to cross to the UK.
‘Bankers’ red carpet’
“The day this relationship unravels, migrants will no longer be in Calais,” Mr Macron told the newspaper, adding that France would also roll out a “red carpet” to London’s bankers if the UK voted to leave the EU.
He also said a country leaving the single market would “not be able to secure the same terms”, and the EU’s “collective energy would be spent on unwinding existing links, not re-creating new ones”.
The migration crisis is among topics expected to be discussed when the UK prime minister and French president meet in Amiens, northern France.
Mr Cameron has also previously claimed migrant camps could move to Englandif the UK left the EU – although his comments were dismissed as “scaremongering” by those campaigning for an EU exit, including his former Defence Secretary Liam Fox.