Lead to more migrants, warns UK government

interior ministers David Blunkett and Nicolas Sarkozy following a series of riots at the Sangatte migrant camp near Calais.

The treaty allowed for joint British and French border controls in Channel ports in France, easing the pressure on Britain’s border force that came from the thousands of migrants from Sangatte who were making daily attempts to board Channel Tunnel trains.

“There are any number of opposition politicians in France who would love to tear up the excellent agreement we have with France,” Cameron said after a speech later in the day.

“I don’t think we should give those politicians any excuse to do that,” he added.

Many in northern France believe that getting rid of British border controls in France would mean the end of controversial migrant camps like the “Jungle” in Calais as well as easing the burden on French police.

Xavier Bertrand, the newly-elected head of the northern French region that includes the port of Calais, said the British government’s comments meant that revising the treaty was “no longer taboo”.

Bertrand, from the opposition Republicans party, hailed the comments as “a turning point”.

If Britain were to leave the European Union “they would automatically take the border back. If they stay, we cannot remain as we are,” he added.

The warning about migrants arriving in Kent was described as a political move by Cameron ahead of the referendum.

“Arguments to this effect are likely to play a significant role in the campaign, on both sides of the referendum question,” said Marley Morris of think tank IPPR.

“But our research suggests that claims that EU migration will remain high or increase in the event of Brexit do not wash with the public.”

Cameron’s words were quickly contested by the anti-EU campaigners, who said the border deal would not be affected by the country’s EU membership status.

Arron Banks, co-founder of the Leave.EU campaign, accused Cameron of “scaremongering”.

“The agreement we have to process migrants in Calais is with France, not the EU. There is no reason for this to change on leaving the EU,” he said.

Immigration is the central issue for many Britons in the debate over whether Britain should stay or leave the European Union ahead of an in-or-out referendum expected to be held later this year.

Recent opinion polls indicate that more Britons want to leave than want to stay and experts say attitudes have hardened in reaction to Europe’s migrant crisis.

Rob Whiteman, a former head of the UK Border Agency, supported Cameron by saying Brexit would mean “almost certainly” that France would end the treaty.

“There has been lots of upsides for the UK since the treaty was negotiated in 2003, not much upside for the French,” he told BBC radio.

“Before that treaty was put in place, asylum claims were running at 80,000 a year in the UK. They are now running at about 30,000 a year so we would probably see, let’s say, another 50,000 asylum claims a year which we used to get before the treaty came in.”

Cameron promised to renegotiate the UK’s relations with the EU. The renegotiation will be followed by a referendum by the end of 2017, to decide whether or not the United Kingdom should remain in the EU.

If he achieves the reforms, Cameron will campaign to stay in. Otherwise, the Conservatives might campaign to leave the EU.

This decision could have far-reaching consequences for trade, investment and Great Britain’s position on the international scene.

Some other European countries are ready to listen to Cameron’s concerns on issues such as immigration, and may be prepared to make limited concessions to keep Britain in the bloc.

But EU leaders also have their red lines, and have ruled out changing fundamental EU principles, such as the free movement of workers, and a ban on discriminating between workers from different EU states.