The Irish president has said his decision to decline an invitation to a Northern Ireland’s centenary event alongside the Queen came after six months of consideration.

Michael D Higgins said he had raised concerns about the title of next month’s proposed church service from March of this year.

“That’s the beginning, so it isn’t a sudden decision, the decision is the outcome of a consideration,” the president said.

Mr Higgins, who on Friday had an audience with the Pope in Rome, has faced criticism from unionists in Northern Ireland for turning down the invite to the centenary service in Armagh organised by the four main churches in Northern Ireland.

The president said the title of the event, which refers to the partition of Ireland and foundation of Northern Ireland, was not politically neutral and, as such, he felt it was inappropriate for him to attend the service.

In an interview with RTE in Rome, Mr Higgins said he had “no difficulties” appearing at other engagements in Northern Ireland alongside the Queen and insisted he was not involved in any “boycott” of events related to the centenary.

Taoiseach Micheal Martin said he respected the president’s decision not to attend the service.

“I respect the president’s decision and I understand where the president is coming from,” he told reporters in Cork.

“I think he has articulated and has given his reasons and we know that the president has given a lot of time to commemoration, and takes it very seriously.

“He is also very committed to reconciliation. We don’t need to question his bona fides in that respect at all, and people shouldn’t.

“He has a long-standing relationship to peace and reconciliation on the island too.

“I think he has made his decision now and as he said himself, we should move on from this.

“I think the relationship with the United Kingdom and Ireland has been transformed over the last 30 years and this will not harm it in any way.

“I know the president looks forward to working with the Queen, with the UK head of state into the future and will also work to continue to build relationships north and south. That’s where we are right now.”

The leader of the Catholic church in Ireland, Archbishop Eamon Martin, insisted the service was to be “completely non-political” and he expressed surprise at the president’s decision.

“I think it would have been very special if the president had been able to attend and it was a bit unexpected whenever we heard that he wasn’t able to come,” he said.

Earlier, Irish Foreign Affairs Minister Simon Coveney said his department was involved in consultation with the president on the invitation but made clear the decision to decline it was his own.

Mr Coveney, who himself attended an event in Belfast on Friday marking the centenary, said his department did not offer Mr Higgins any “clear advice” on whether he should or should not go to the church service.

In his criticism of Mr Higgins, DUP leader Sir Jeffrey Donaldson had questioned whether it was politically motivated as a consequence of advice from the Irish Government.

Mr Coveney was asked about the extent of engagement between the government and president on the issue.

“There was consultation between the Department of Foreign Affairs and the Aras (president’s official residence) on this issue and many other issues, but I can assure you President Higgins is the kind of person who makes his own decisions,” he said.

“He listens to all perspectives and then makes a judgment for himself.

“And, you know, he’s made his decision on this. He’s given an explanation as to the basis for that decision and I think we need to respect that.”

The minister said he was “not going to second-guess the decisions of the president of Ireland”.

“He makes his own decisions and he makes his own judgment calls, and I respect that.”

Mr Coveney said he hoped the controversy would not set back north-south relations.

“I hope it’s not a setback at all,” he told Friday’s centenary event organised by the Presbyterian Church.

Mr Martin and Mr Coveney both said the Irish government had not yet received an invite to attend the Armagh event. They said if one was received it would be considered.

In an interview with the Irish Times on Thursday, the president denied he was snubbing the Queen.

“There is no question of any snub intended to anybody,” he said. “I am not snubbing anyone and I am not part of anyone’s boycott of any other events in Northern Ireland.

“I wish their service well but they understand that I have the right to exercise a discretion as to what I think is appropriate for my attendance.”

Mr Higgins also challenged the DUP criticism.

“It’s a bit much, to be frank with you. I have gone up to Northern Ireland to take part in events,” he said.

“There often has not been a great deal of traffic down from the DUP people who are criticising me now.”

The president also moved to clarify a report on Thursday that claimed he said the organisers of the event had referred to him as the President of the Republic of Ireland, not the President of Ireland.

He said it was actually the DUP that had referred to him as President of the Republic of Ireland, not the organisers.

“I may be responsible for creating a small confusion and that is the organisers writing to my office have always referred to me as President of Ireland,” he said.

Mr Higgins said that, on the day of the service, he has already agreed to host the Statistical and Social Inquiry Association of Ireland at his official residence at Aras an Uachtarain in Dublin.

Sir Jeffrey accused President Higgins of “retrograde” steps.

“We’re very disappointed with what President Higgins had to say,” he said.

“This service is about hope and reconciliation, that is the theme.

“It’s hosted by the four churches, that in itself is cross community, it is demonstrating in real and tangible ways reconciliation in Northern Ireland and yet it is regrettable that the president feels he can’t attend this.”

Sinn Fein president Mary Lou McDonald said Mr Higgins had made the “correct” decision in declining the invite.

“The partition of Ireland was a catastrophe for our people and our country,” she tweeted.

“The partition of Ireland costs us to this day, holds us back, divides us.”