Theresa May has conceded that a border agreement between Britain and France could be up for renegotiation following the victory of Emmanuel Macron in the French presidential contest.

Le Touquet 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, in Calais, rather than on British soil.

But during the campaign for the keys of the Elysee Palace, Mr Macron said he wanted to put Le Touquet agreement “back on the table”.

When asked about the decade-old agreement during a campaign rally, Ms May replied: “As for Le Touquet agreement, actually it works for the benefit of both the UK and France.

“Obviously the government elected after 8 June will be sitting down and talking to Monsieur Macron and others about how that system we have works for the benefit of France as well as the benefit of the UK.”

The Prime Minister also asked voters to give her an electoral mandate as significant as Mr Macron’s in order to make it easier for her to negotiate Britain’s exit from the European Union. “Yesterday a new French president was elected,” she said. “He was elected with a strong mandate which he can take as a strong position into the negotiations.

“In the UK, we need to ensure that we’ve got an equally strong mandate. Every vote for me and my team will strengthen my hand in those Brexit negotiations.”

Mr Macron has previously suggested he would renegotiate the agreement that allows British border police to operate in Calais, adding he wanted “to put the Le Touquet border deal back on the table” in an interview with the French television channel TF1.

He added: “It must be renegotiated, especially the parts that deal with the fate of isolated child migrants… there is no easy solution to the migrant crisis. If there was one, it would have been found.”

Emmanuel Macron at his victory speech in Paris on Sunday (Getty) ( Getty Images )

During his campaign, the President-elect added that he will be “pretty tough” in the Brexit negotiations and that his goal will be to “preserve the rest of the EU and not to convey the message that you can decide to leave without any consequences.”

Appearing at a campaign rally in north London, flanked by candidates for the party at the general election, the Prime Minister also explicitly said the Conservatives would introduce caps on energy prices and retain the commitment to reducing migration to the “tens of thousands” despite failing to deliver on the pledge since 2010.

Ms May said: “I think it is important that we continue, and we will continue, to say that we do want to bring net migration down to sustainable levels.

“We believe that is the tens of thousands, and of course once we leave the European Union we will have the opportunity to ensure that we have control of our borders here in the UK, because we’ll be able to establish our rules for people coming from the European Union into the UK.”

Emmanuel Macron says he will defend France and its vital interests

Net migration hit a record high of 336,000 last year, up from 252,000 in 2010 when Mr Cameron took power. Net migration would have to be below 100,000 to hit the Conservatives’ target.

Against posters branding the candidates Theresa May’s Team, she called on supporters to “work flat out” in the run up to the 8 June poll. “We must go out there and leave no stone unturned, no street unwalked down, no door unknocked on.

“Every vote counts because every person counts and every community counts,” she said. “I’ve learnt how important it is to get out there, to speak directly to voters and to listen to their concerns.