The French presidential frontrunner Alain Juppé has said he would likely scrap the decade old Le Touquet agreement with the UK and place the border between the two countries on British soil.

The agreement, drawn up as part of a bilateral treaty between the two countries, allows the UK to operate its border controls on the French side of the channel.

During the European Union referendum campaign David Cameron was accused of scaremongering when he said leaving the union would lead to the deal being scrapped – and the refugee and migrant camps in Calais relocating to southern England as a result.

The French government dismissed the claim from the Prime Minister at the time and said it had “no plans” to change the agreement. However, Sir Peter Ricketts, former UK ambassador to France and former national security advisor to Mr Cameron warned that France’s stance might not last forever.

But speaking to the Financial Times, Mr Juppé, who is leading in opinion polls, said: “The logic requires that border controls take place on British soil.”

“We must move the border back to where it belongs,” he added.

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The Calais 'jungle' camp that has grown up in the past two years as thousands of migrants seek to avoid border controls there and reach Britain illegally through the Channel Tunnel is controversial on both sides of the Channel.

The number of people living in the camp is small compared to the total number of refugees entering Europe as a whole – with millions entering the continent in 2016, according to a European Commission estimate.

Calais and Dunkirk camps Show all 16 1 /16 Calais and Dunkirk camps Calais and Dunkirk camps (Photo: Alan Schaller) Calais and Dunkirk camps A portrait of an Afghan man wearing a traditional Perhan Turban in the Calais Jungle (Photo: Emily Garthwaite) Calais and Dunkirk camps Two Gendarmes guard the main entrance to the Dunkirk camp (Photo: Emily Garthwaite) Calais and Dunkirk camps One Kurdish Iraqi man’s reminder to himself (Photo: Alan Schaller) Calais and Dunkirk camps Two young boys in the Dunkirk camp (Photo: Alan Schaller) Calais and Dunkirk camps An Iranian hunger striker stands outside the only remaining shelter in the South Side of the Calais camp (Photo: Emily Garthwaite) Calais and Dunkirk camps A church in the South Calais camp, on of the the only structures not demolished in the South Side of the camp (Photo: Emily Garthwaite) Calais and Dunkirk camps A man gets a hair cut in the Calais camp (Photo: Alan Schaller) Calais and Dunkirk camps Night falls on the Calais Jungle. Fires burn in the distance (Photo: Alan Schaller) Calais and Dunkirk camps The containers provided as alternative accommodation for the people in the camps (Photo: Alan Schaller) Calais and Dunkirk camps A young boy in the Dunkirk camp (Photo: Alan Schaller) Calais and Dunkirk camps A man listens to music inside one of the shipping containers (Photo: Emily Garthwaite) Calais and Dunkirk camps The awful living conditions in the Dunkirk camp (Photo: Alan Schaller) Calais and Dunkirk camps An Afghan man in the Calais camp (Photo: Emily Garthwaite) Calais and Dunkirk camps One of the Iranian hunger strikers (Photo: Alan Schaller) Calais and Dunkirk camps A family in their wooden shelter in the new Dunkirk camp (Photo: Alan Schaller)

Mr Ricketts said earlier this year that the French government was using up significant political capital and police resources in its operation in Calais and that opposition parties were keen to pull out of the agreement.

“This treaty is a bilateral treaty but it was made in a multilateral context where Britain and France are working together across a whole range of issues,” he told BBC Radio 4.