Former UK attorney general Dominic Grieve has said the chances of an Irish border poll will “go up” if Britain crashes out of the EU without a deal.
The Conservative MP said the status of Northern Ireland would be “thrown into jeopardy” in the event of a no-deal scenario, and he is also worried about the union in terms of Scotland.
He said the risk of violence post-Brexit if there is a no-deal withdrawal is also a concern.
Mr Grieve made the comments ahead of a speech at the Institute of International and European Affairs in Dublin on Friday.
He said: “A crash-out Brexit makes a political crisis in respect of Northern Ireland’s future status more likely… clearly the chances of a border poll go up for a whole variety of reasons.
“The status of Northern Ireland under the Good Friday Agreement remaining in the UK has worked because in truth there’s been a clear majority of the population who have been very comfortable with the arrangements that the Good Friday Agreement has delivered, and that includes sections of the nationalist community as much as the unionist, and that will be thrown into jeopardy by a no-deal Brexit.
“Indeed Brexit itself is probably likely to put it under strain even if it is done in a controlled fashion.”
Mr Grieve said potentially bringing about Irish unification through the mechanism of Brexit had always struck him as being “a very bad idea”.
Asked whether a no-deal Brexit raises the risk of violence in Northern Ireland, Mr Grieve said the prospect does concern him.
“It worries me because I think I know Northern Ireland well enough to know that acceptance of change, even if you have a minority status, doesn’t always follow,” he said.
“After all the whole history of the Troubles was of a series of perfectly clear grievances held by sections of the Northern Ireland community which meant that they wouldn’t accept ordinary democratic processes in Northern Ireland because they felt that as a result, their status and way of life was under threat and they were also discriminated against and there were enough of them to create violence.
“And in the exactly same way, in my view, the same exists within the loyalist community.”
Mr Grieve said he would be “very surprised” if Boris Johnson does not win the Conservative Party leadership race, and that he expects a “period of major political crisis” in the coming months – especially in the eight weeks in the lead-up to the October 31 Brexit deadline.
He added he has no desire to see a general election because he is “not sure” it would resolve anything in the current political climate.
Instead, he is in favour of a second referendum on EU withdrawal being held.
“It’s the only way out of the current crisis,” he said.
“I also accept that some people think that Boris Johnson will be able to negotiate a fresh deal and get that deal through Parliament. It’s possible, but personally I think it’s unlikely.”
He also said he does not believe the UK will leave the EU without a deal.
But he added: “He [Boris Johnson] must realise that a no-deal Brexit is a really bad idea for the United Kingdom but equally he’s made a series of promises, because we’re in the middle of a leadership election campaign where in order to get elected you need to make promises which have an appeal to a very restricted section of the electorate.”
He said having made those promises, it might be “quite difficult” for Mr Johnson to escape from them.