The DUP leader made the remark during an interview with the comedian Patrick Kielty for a BBC documentary in which Mr Kielty explored the 20th anniversary of the Belfast Agreement and the murder of his father by loyalist terrorists.

Mr Kielty asked Mrs Foster “if the majority did want to join the rest of Ireland how would it feel to be a unionist, outside of the UK?”

Alluding to years of polling which has shown strong support for the Union, the former first minister replied: “First of all, I don’t think it’s going to happen.

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Arlene Foster made her comments in an interview with Patrick Kielty which was broadcast on BBC One on Wednesday night

“It’s a very hypothetical situation to be in but if it were to happen, I’m not sure that I would be able to continue to live here, I would feel so strongly about it. I would probably have to move.”

Mr Kielty asked Mrs Foster where she would move if that was to happen, to which she replied: “Well that’s the question. It’s not going to happen so I don’t have to worry about it, I don’t think, anytime soon.”

Mrs Foster’s family had to move in traumatic circumstances in 1979. The Kelly family moved from their rural farm near Rosslea – closer to the Irish border, little more than two miles away, than to the county town of Enniskillen – after the IRA shot her father in the head in an attempt to murder him in 1979.

The TUV leader Jim Allister, a vocal hardline critic of the DUP, said that he understood the sentiment behind Mrs Foster’s comment.

Arlene Foster made her comments in an interview with Patrick Kielty which was broadcast on BBC One on Wednesday night

He said that “as the son of parents who left the Irish Republic after it became the Irish Republic” he could “totally understand the sentiment” behind the DUP leader’s concern.

Mr Allister’s parents moved from Co Monaghan to Northern Ireland in 1950 because they felt “the noose was tightening” on them as Protestants in a state where the Roman Catholic Church had enormous influence.

He said: “I think it’s very clear that any all-Ireland would be a very cold house for unionists so I wouldn’t be surprised at what she said.”

However, other senior unionists said that they would not leave their homes. Former Ulster Unionist leader Tom Elliott, a traditional rural unionist who comes from the same Fermanagh constituency as Mrs Foster, said that it was a question that he had “never given any real thought to - but hypothetically if it were to happen my immediate sense wouldn’t be to leave.

“Certainly, you’d think about all these things if it did happen or was imminent, but it’s not something that’s ever crossed my mind at all. My initial reaction to it would be not to leave.”

Mr Elliott, who lost his seat as an MP in last year’s General Election and who now farms, added: “To me, it’s still home.”

He said that he had never heard the issue ever discussed by unionists because it was seen as such a remote possibility that it was not worth considering.

The current leader of the Ulster Unionist Party, Robin Swann, said that with such a hypothetical question “there is a danger that you validate the argument by even having the debate, when the reality is that a united Ireland is not on the horizon”.

However, he went on: I have never run away from a fight in my life and I will do all I can to ensure that Northern Ireland remains part of the United Kingdom by persuading people of the very real benefits of remaining part of the sixth largest economy on the planet and a Union that has served Northern Ireland and its people well.

“This is my home. It is the only home I have ever known and I will not be leaving it.”

He added: “Given the experience of unionists in Southern Ireland post-partition, it is perhaps not surprising that some unionists in Northern Ireland would view the prospect of Irish unity with trepidation.

“But history also tells us that as a people we do not frighten easily.”

And veteran DUP MP Jim Shannon was clear that he would not contemplate leaving. He told the News Letter: “Will I ever leave? What I have I hold,” adding that he believed that there were “enough of us of both persuasions” to maintain Northern Ireland’s place within the Union so the question would never arise in anything but a hypothetical sense.

He added: “My grandfather’s in his grave here; my dad’s in his grave here; my children are married here and my life is here - I don’t see that changing.”

He added: “Then again, I don’t think it will ever happen, so I can say with confidence that I will not be leaving here.”

SF once wanted to pay unionists to move

Sinn Féin once advocated paying unionists to leave Northern Ireland in the event of a united Ireland being created without a majority north of the border accepting that outcome.

In 1987 – four years into Gerry Adams’ 34-year tenure as president of Sinn Féin – the party published a document called ‘A Scenario for Peace’.

The document, which remains on the Sinn Féin website, said: “Anyone unwilling to accept a united Ireland and wishing to leave should be offered resettlement grants to permit them to move to Britain, or assist them to move to a country of their choice”.

The proposal it set out was in the context of a time when Sinn Fein refused to accept that a majority in Northern Ireland should have to vote for a united Ireland if the border was to be removed.

Sinn Féin denounced that as a ‘unionist veto’, because Northern Ireland’s boundaries had been drawn to ensure a healthy support for maintaining the Union.