UK Prime Minister Keir Starmer has rowed back from a commitment to campaign for the Union in any future border poll, saying he would be "an honest broker" on the issue.
Mr Starmer was asked about a possible poll after meeting the main political parties at Stormont.
He has described himself as a Unionist and previously said he would campaign for Northern Ireland to remain part of the UK if a referendum was held in his lifetime.
Speaking during a visit to Northern Ireland in October, the Labour leader appeared to rule out calling a poll if he became prime minister, saying it was "not even on the horizon".
However, today Mr Starmer took a much more neutral position.
"This is provided for by the Good Friday Agreement. The framework is set out and I'm absolutely committed to the Good Friday Agreement," he said.
"Today is a recommitment to that and to the approach and the role of the UK government in that as the honest broker."
Mr Starmer also again stressed his desire to rebuild relations with the Irish Government, which were seriously damaged by the approach of successive Conservative governments.
He would not be drawn on the Irish Government's legal challenge in the European courts to the UK's controversial Troubles legacy act, which ended all investigations.
The issue will be discussed when Taoiseach Simon Harris visits Downing Street next week.
"I've already had discussions with the Taoiseach and others, again to make it clear the approach that I will take to reset and make sure those relationships are collaborative, and they're respectful," he said.
"Of course there are issues including in relation to litigation, but the most important thing is the way in which we will approach this and I treat the mandate that I was given in the general election as a mandate for doing politics differently".
Earlier, Mr Starmer met the First and Deputy First Ministers.
He discussed parliamentary schedules at Westminster and Stormont with First Minister Michelle O'Neill and Deputy First Minister Emma Little-Pengelly as they met at Stormont Castle.
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Ms Little-Pengelly told the prime minister the power-sharing executive was working on its programme for government.
They were joined by new Northern Ireland Secretary Hilary Benn.
Mr Starmer is on a tour of the UK following his landslide win in last week's general election.
He was later greeted at Parliament Buildings by Assembly speaker Edwin Poots.
Four pro-Palestine protesters shouted and waved Palestine flags as the prime minister arrived.
DUP leader Gavin Robinson said he talked to Mr Starmer about the ongoing financial challenges facing people in Northern Ireland.
Mr Robinson said: "We had the opportunity not only to talk to him about the importance of devolution in Northern Ireland but the political process itself and the need for a proactive British government to carefully nurture relationships within Northern Ireland.
"We talked to him about the ongoing challenges to deliver for people of Northern Ireland."
Mr Robinson said it had been a "productive discussion".
He added: "He has the opportunity to make significant changes and advance things positively."
Alliance party leader Naomi Long said she hoped the Labour government would mark a "new start" in terms of relations with Northern Ireland.
Speaking after meeting Mr Starmer, she said: "We had the opportunity to raise with him the importance of the impartiality of government in terms of its engagement with local parties and with the Assembly.
"I think he understands how important that is given his history in working in Northern Ireland.
"It also gave us an opportunity to talk to him further about some pressing issues, in particular I raised the issue of legacy."
SDLP leader Colum Eastwood said that Mr Starmer understands Northern Ireland.
"Keir Starmer is somebody who gets it, he understands this place, he has been here many times, he worked here and he knew the issues before we even raised them.
"Even saying that, we still raised them. This place needs more money to function, our health service is at the point of collapse and can't survive much longer without a proper injection of funding.
"We also talked about the issue of Casement Park which needs to be built and needs to be built as soon as possible," Mr Eastwood said.
In a statement in advance of the meetings, Mr Starmer said his government will work "with all communities, political parties, and with respect to all traditions".
Mr Benn has pledged to work with the Irish Government on a new approach to dealing with the legacy of the Troubles, confirming the Labour Party's commitment to repeal and replace the controversial Legacy Act.
He also gave a commitment that the GAA's planned new Casement Park stadium in west Belfast will be built, but could not give any guarantee that it will be completed to host the Euro 2028 championships.
Mr Starmer and Mr Benn have also said resetting British-Irish relations, which have been severely damaged in recent years, will be a priority.
In his statement, Mr Starmer said stability and long-term certainty will be at the centre of everything his government does in Northern Ireland.
"We are the party of the Good Friday Agreement, and the stability it has brought," he said.
"Together, as we take the steps towards a decade of national renewal, we will harness Northern Ireland's vast economic strengths - rebuilding strong public services and generating real and tangible economic growth for working people.
"We must turn the page and secure investment, prosperity, and stability for generations to come."
Sinn Féin leader Mary Lou McDonald, whose party last week emerged as the largest Northern Ireland party at Westminster following the general election, said she used her meeting to urge Mr Starmer not to "bury his head in the sand" on the question of Irish unity.
Ms McDonald said last week's election result reflected again that "all is changed here and changing".
"We have reiterated our view to the prime minister that it is foolhardy to bury your head in the sand on this question.
"We have reminded him that the provision for referendums is at the very heart of the Good Friday Agreement.
"Yes, we need to see progress on this, yes we need if people talk about conditions for a referendum, let's have clarity on what is meant by that.
"This is a question that needs to be addressed by all of us."
Additional reporting PA
