Pope Francis will make a ground-breaking visit to Northern Ireland when he travels to Ireland in 2018, Northern Ireland's Deputy First Minister has predicted.

Within moments of the Pontiff confirming a widely-expected trip to Dublin for a global gathering of the Catholic Church, Martin McGuinness said there was "no prospect" of him not crossing the border.

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"I think there is no prospect whatsoever of him coming to Ireland and him not coming to the North," he said.

Asked how why he was so sure, he replied: "Because I'm around a long time and I know how these things work."

Pope John Paul II was unable to cross the border into Northern Ireland during the last papal visit in 1979.

Instead, amid a welter of security fears and cross-community tensions, the then pope travelled as far as Drogheda, just south of the border, for a huge audience.

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Taoiseach Enda Kenny confirmed Pope Francis would travel to Ireland in August 2018 after a 23-minute meeting with him in the Vatican on Monday morning.

The Irish capital is hosting the two-day World Meeting of Families, a gathering of the church.

After his audience with the Pope in the Apostolic Palace, Mr Kenny tweeted: "Pope Francis has been an important voice for the young, the poor & disadvantaged - glad he will visit Ireland in 2018."

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Later, he told reporters: "We discussed what he might do and obviously that is a matter for His Holiness and the bishops and if that means that he also travels to Northern Ireland, then we will co-operate and assist in whatever arrangements are arrived at."

Earlier this year, Catholic Archbishop of Dublin Diarmuid Martin said Irish bishops would like the Pope to visit Northern Ireland during his expected trip to Dublin.

"The programme has not yet been defined ... but I think that a visit to Northern Ireland, even a short visit, of a political nature, of an ecumenical nature ... will be very important," he said at the time.

"Pope Francis has this tendency to make important gestures of reconciliation ... And I suspect that when we start to talk about this trip, Pope Francis will surprise us all with some highly symbolic gesture."

Mr Kenny's meeting with the Pope will be seen as a milestone in the thawing of relations between Dublin and the Vatican over recent years.

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Just five years ago, amid a wave of inquiries into decades of clerical child sex abuse in Ireland, the Taoiseach branded the Holy See "a dysfunctional, elite hierarchy" which was determined to frustrate the investigations of "a sovereign, democratic republic".

The Vatican recalled its ambassador to Ireland just days after the unprecedented attack by an Irish premier on the Catholic Church hierarchy.

The Irish Embassy to the Holy See in Rome was also shut that year, ostensibly as a cost-cutting measure.

Three years later, Dublin announced plans to reopen it.

The timing of Pope Francis's planned trip to Ireland has already raised concerns that it could clash with a potential referendum on the country's abortion laws.

A Citizens Assembly is considering the Eighth Amendment to the Constitution, which recognises "the right to life of the unborn, with due regard to the equal right to life of the mother".

It will recommend possible reforms next year.

Transport, Tourism and Sport Minister Shane Ross said a papal visit would likely boost tourism but he voiced worries about the timing.

"I simply think that maybe there are better times to come than in the middle of a controversial political matter in which he might get embroiled," he said.

Mr Kenny said he would wait to see what the Citizens Assembly recommends, adding that a referendum would not be held in the month of August in any event.

"We discussed a range of other matters in regard to the state of the Church and State relations in Ireland," he added about his meeting with the Pope.

"I explained to him my own difficulties with the Church some years ago and I was happy to confirm to him that Church and State relations are now in better shape than they were for very many years."

On Northern Ireland, Mr Kenny said: "If it transpires that the Pope wants to go to Northern Ireland, to any part of Northern Ireland, for a visit then we will co-operate and work with the (Northern Ireland) Executive."