Theresa May admitted there could be no open border in Ireland if Britain outside the EU, newly emerged video shows

The Prime Minister gave an interview before the referendum saying there would 'have to be' a border if Britain left the EU

A video has emerged of Theresa May admitting there cannot be an open border between Northern Ireland and the Republic, if Britain leaves the EU.

The Prime Minister, who was Home Secretary at the time, said there would “have to be” some sort of border to recognise that tariffs may be charged on goods entering and leaving the UK and to account for different immigration rules.

It comes amid a major clash between EU negotiators and Ms May, who yesterday said Brussels’ plans for the Irish border are “unacceptable”.

In the video, recorded on June 21, 2016, two days before the referendum, Ms May said: “Just think about it.

“If we are out of the European Union with tariffs on exporting goods into the EU, there’d have to be something to recognise that, between Northern Ireland and the Republic of Ireland.

“And if you pulled out of the EU and came out of free movement, then how could you have a situation where there was an open border with a country that was in the EU and has access to free movement.”

Yet since becoming Prime Minister, Ms May’s approach to Brexit has seen her insist the UK can leave the EU and its customs union while also keeping the border in Ireland all but open – something which is seen by many as critical to peace in the region.

EU officials have dismissed her approach, and said if the border remains open between Northern Ireland and the Republic, there must also be regulatory alignment between the two areas, and a customs border in the Irish Sea to catch goods moving to the unaligned UK, if Ms May takes the country out of the customs union.

Yesterday the Prime Minister said in the Commons that the EU’s proposals would undermine the integrity of the UK and could not be accepted by any British leader.

Labour MP Chuka Umunna, a supporter of the Open Britain group which dug out the film, said: “Before the referendum, before she became Prime Minister, and before she was dependent on the DUP to drive through her plans for a hard Brexit, Theresa May told the truth – if we leave the customs union and the single market there will be a hard border in Ireland.

“It is imperative that Ms May uses her ‘Road to Brexit’ speech tomorrow to be honest with the people of our country about what the consequences of her hard Brexit policy are.

“She needs to drop the dishonesty and face down the extreme Brexiteers in her party.”

A Downing Street spokesperson said the Government does understand the “complex challenges” that Brexit presents for the Northern Irish border, and is committed to finding a way forward with all parties.

He added: “We published a paper on this in the summer, and stand behind what we set out jointly with the EU in December. We look forward to discussing this further with the EU as part of negotiations on our future partnership.

“We’ve been absolutely clear there will be no hard border between Ireland and Northern Ireland, and Northern Ireland’s position within the common market of the UK will be protected.”

Ms May spent the morning meeting with her Cabinet and discussing the speech which she will deliver tomorrow afternoon.