France should tear up the deal which imposes British border checks on migrants in Calais unless radical changes are made, a senior politician has warned.
Xavier Bertrand, president of the Hauts-de-France Nord Pas De Calais-Picardie region which includes Calais, has called for action to deal with the sprawling Jungle migrant camp.
His comments come after Nicolas Sarkozy, the former French leader who is running for his party's nomination for next year's presidential race, called for border controls to be shifted to Britain.
Under the Treaty of Le Touquet, British immigration officials check passports in Calais and their French counterparts do the same in Dover.
Mr Bertrand wants a new deal in which migrants hoping to claim asylum in the UK would be able to do so at a "hotspot" in France. Those who failed would be deported directly to their country of origin.
He told the BBC Radio 4 Today programme he wants a "new treatment" for asylum seekers trying to get to Britain from France.
He said: "Where is it possible to have this kind of treatment? In England or in France? That is the beginning of the discussion.
"If the British Government don't want to open this discussion, we will tell you Touquet Agreement is over."
Thousands of migrants and asylum seekers are living in cramped makeshift tents in the Jungle camp, where outbreaks of disease are common. They frequently clash with police as they try to sneak into lorries and smuggle themselves into Britain.
John Vine, the former independent inspector of borders and immigration, told Today that France and Britain devised the treaty to deal with the previous refugee camp at Sangatte, which was hit by riots in the early 2000s.
He said: "If this arrangement were to end, one of the biggest impacts on us would be potentially a rise in the number of people coming to Britain to claim asylum.
"For the French, of course, the benefits were to rationalise the position they found themselves with with Sangatte.
"And the danger of changing the arrangement for them is that it will encourage, potentially, more people to travel through France if they feel it is easier to get to Britain."
He added: "The arrangement benefits Britain enormously at the moment, so any diminution of the arrangement would have an impact on border control and asylum policy."
Prime Minister Theresa May and French President Francois Hollande in July affirmed their shared commitment to keeping border controls in Calais.
Under current rules, refugees must register in the first European country they arrive in and this country usually takes charge of their asylum claim.
However, the refugee crisis threw the system into turmoil as hundreds of thousands of migrants poured into a small number of countries such as Greece and Italy.
Charlie Elphicke, Conservative MP for Dover, said: "The current situation in Calais is shameful. We do need a new and stronger treaty with France. We must work together to dismantle the Jungle migrant camp.
"We need a new Dover Patrol guarding the English Channel to help catch and jail the people traffickers and end their evil trade of modern slavery. And we must work together to protect our truckers, whose lives are being put at risk in Calais.
"Yet it would be a big mistake to enable people to apply for UK asylum from France. It would just make Calais a bigger magnet for migrants.
"Axing the treaty altogether would be a disaster for France and Britain. It would simply force the ferries and Tunnel to become border guards - meaning higher ticket prices and longer queues.
"We need order at the border. That means both Britain and France must work together to deal with the causes of the problem once and for all."