Leading Conservatives on both sides of Britain’s referendum debate have warned that border controls with the North could be introduced if the UK votes to leave the European Union.

Former chancellor Nigel Lawson, who is chairman of the Vote Leave campaign, said that checks would be needed along the Border to prevent illegal immigration.

“That could be stopped. There would have to be border controls, but not a prevention of genuine Irish coming in,” he told the BBC’s Andrew Marr Show.

Justice minister Dominic Raab, who is also campaigning for Britain to leave the EU, agreed that Brexit could see an end to the open border between the two parts of Ireland.

“If you’re worried about border controls and security . . . you couldn’t leave a back door without some kind, either of checks there with any country or assurances in relation to the checks that they’re conducting, obviously.

“Otherwise, everyone with ill will towards this country would go round that route,” he told Dermot Murnaghan on Sky News.

Energy secretary Amber Rudd, who wants Britain to remain in the EU, said that reintroducing border controls could not be ruled out in the event of a vote to leave on June 23rd.

“We’d have to wait and see but what that does highlight is the very dangerous prospects that are out there if we do leave the EU. The lack of certainty is what concerns me,” she told Andrew Marr.

Brexit threats

David Cameron’s government has warned of the danger of border controls with the North and a threat to the Common Travel Area between Britain and Ireland in the event of a Brexit vote.

Until now, Leave campaigners have dismissed such warnings as scaremongering, with London mayor Boris Johnson insisting in February that arrangements between Britain and Ireland would remain unchanged.

“There’s been a free travel area between the United Kingdom and the Republic of Ireland for, I think, getting on for 100 years. There’s no reason at all why that should cease to be the case,” he said.

Lord Lawson suggested that, despite the need to introduce border controls, the privileges enjoyed by Irish people living in Britain would survive a British vote to leave the EU.

“We’ve allowed the Irish, for example, to vote in British elections. We don’t allow anybody else who’s not British to vote in British elections.

“The Irish are, for historical reasons, a special case and they will remain a special case. The Anglo-Irish relationship is a very, very special relationship and it will continue to be so. It has been ever since Irish independence was secured,” he said.

More than 400,000 people born in Ireland live in Britain and Minister for Foreign Affairs Charlie Flanagan last week urged them to get involved in the campaign to keep Britain in the EU.