There are concerns any change in France could jeopardise existing agreements
Britain and France have pledged to work together to address the Calais migrant crisis - after the British government made clear it will resist attempts to change the agreement on border checks there.
British home secretary Amber Rudd travelled to France for discussions with interior minister Bernard Cazeneuve in which both countries "re-affirmed their commitment to closer co-operation on counter-terrorism, security and migration".
But border security was propelled to the top of the agenda after calls by senior French politicians, led by former president Nicolas Sarkozy, to move checks on refugees & migrants from Calais to the UK.
Mr Sarkozy, who hopes to make a comeback in the French presidential election next year, said the controversial "Jungle" refugee & migrant camp in Calais should be shut down and moved to Britain.
There have also been suggestions people could be allowed to lodge UK asylum claims on French soil.
Xavier Bertrand, president of the Hauts-de-France Nord Pas De Calais-Picardie region which includes Calais, wants a new deal in which people hoping to claim asylum in the UK could do so at a "hotspot" in France.
At their meeting in Paris back in July, British prime minister Theresa May said she had won a pledge from the French president Francois Hollande on the existing deal despite the UK's vote to leave the EU.
President Francois Hollande agreed, and said the agreement was useful to both countries.
"We consider it as our duty ... to apply it and also to improve it," he added.
Under the Treaty of Le Touquet, British immigration officials check passports in Calais and their French counterparts do the same in Dover.
The problem for the British government is that if Mr Hollande loses the presidential election next year, the existing treaties and agreements could be in jeopardy.
Asked about reports the UK may withdraw security co-operation with France if it tears up the agreement on Calais, a Downing Street spokesman said: "France is one of our most important allies in Europe and I wouldn't get drawn on speculation about some suggestions that we may or may not be withdrawing co-operation.
"Our relationship with France remains as strong as it ever has done and will continue to be so ... We have worked incredibly closely together and we will continue to work incredibly closely together."
"The position in Calais remains the same. We are committed to that border, the French are committed to that border, the processes that are engaged at that border will continue."
British Labour leader Jeremy Corbyn insisted it was Britain's "moral duty" to help share the impact of the refugee crisis across the continent.
"I have visited the camps in Calais and Dunkirk and I've seldom seen anything so disgusting as those pathetic camps in a land of plenty.
"It's not right, and not necessary, and I have raised this issue with French authorities as well as our own."