By Costas Pitas

LONDON (Reuters) - France's Alain Juppe will move the border with Britain from Calais to southern England if he wins power next year, setting up a potential battle with London over immigration following the Brexit vote, the Guardian newspaper reported.

Thousands of migrants from countries such as Afghanistan, Ethiopia and Eritrea live in a ramshackle camp beside the English Channel that is known as the Jungle, a symbol of Europe's biggest migrant crisis since World War Two.

With thousands of people seeking to reach British shores, fences have been erected around the entry to the Channel tunnel and British opponents of mass immigration cast the Jungle as a danger to Britain during the EU referendum.

Juppe, who is on course to win the center-right's presidential ticket and favorite to win power in next year's national election, said he would seek to overturn a treaty which effectively pushes the British frontier to France.

"The first thing is to denounce the Le Touquet accords," Juppe told the Guardian newspaper in an interview.

"We cannot accept making the selection on French territory of people that Britain does or doesn't want. It's up to Britain to do that job," he was quoted as saying.

In 2003, Britain and France signed an agreement - known as Le Touquet accords - which allows British officials to check passports in France and vice versa.

French President Francois Holland has vowed to close the Jungle camp. Though previous efforts to disperse the camp have failed, France is expected to move the migrants from their makeshift houses next week.

"We can’t tolerate what is going on in Calais," Juppe was quoted as saying. "The image is disastrous for our country and there are also extremely serious economic and security consequences for the people of Calais."

Any move to scrap the understanding will likely be resisted by British Prime Minister Theresa May, who has said that cutting immigration is a key priority after Britons voted to leave the European Union.

Former Prime Minister David Cameron warned ahead of the June 23 referendum that France could seek to cancel the Le Touquet agreement in the event of Brexit, leading to an influx of asylum seekers into Britain, but Paris has since said it will respect the agreement.

France transferred several dozen mostly Afghan teenagers to Britain this month as efforts to remove the most vulnerable migrants of camp. There are an estimated 1,000 unaccompanied children in the camp.

(Editing by Guy Faulconbridge and Alison Williams)