Francois Hollande has hinted France could scrap the current deal which stops thousands of migrants in Calais from entering the UK if Britain votes to leave the EU.
The French president warned of "consequences" from a Brexit as he hosted David Cameron at a Franco-British summit in the city of Amiens.
But Brexit campaigner Boris Johnson responded with a little schoolboy French to accuse the French government of scaremongering.
ITV News Deputy Political Editor Chris Ship reports from Amiens.
'Donnez-moi un break' was Boris Johnson's response when was asked about claims a Brexit could see the Calais 'Jungle' camp move to the UK.Read the full story ›
Boris Johnson has accused David Cameron of 'clutching the skirts of Europe' and urged voters to chose 'Project Hope' over 'Project Fear.'Read the full story ›
Russell Brand has accused Boris Johnson of growing "Jihadi Johns" terrorists in a bizarre online rant.Read the full story ›
David Cameron has warned the EU referendum will be a “final decision” on Britain’s membership of the union.Read the full story ›
London Mayor Boris Johnson has said the referendum is a "once in a lifetime chance" to vote for real change in Britain's ties with Europe.Read the full story ›
Boris Johnson is among 40 MPs to have signed a letter in the Sunday Telegraph urging a relaxation of Sunday trading laws.Read the full story ›
ITV News' Political Editor Robert Peston understands the Mayor of London, Boris Johnson, will be joining the campaign to leave the European Union.
Mr Johnson is expected to formally announce his decision to align with the 'leave' camp against the Prime Minister on Sunday evening.
London Mayor Boris Johnson will publicly announce whether he backs a Brexit on Friday.
Mr Johnson "will make everything abundantly clear by the end of the week" about his choice of camp in the referendum battle, sources said after the talks.
He was called to Downing Street for talks with the Prime Minister earlier today.