Pope Francis has said that he is praying the Good Friday Agreement - signed 25 years ago today - can be "consolidated" to benefit the people of all of Ireland.
He made the comment in his Easter Monday address to tens of thousands of people in St Peter's Square.
"Today marks the 25th anniversary of the so-called Good Friday agreement, or of Belfast, which brought an end to the violence that for decades troubled Northern Ireland," Pope Francis said.
"In a spirit of gratitude I pray to the God of peace so that what was achieved in that historic step can be consolidated to benefit all the men and women of the island of Ireland," he added.
Earlier, British Prime Minister Rishi Sunak praised the bravery and compromise exhibited by the leaders who secured the agreement as he called for power-sharing to swiftly return to Northern Ireland.
Mr Sunak celebrated the "difficult decisions" taken and "political imagination" displayed to end the Troubles.
"So we must get on with the business of governance," he said in a statement.
Mr Sunak will host US President Joe Biden in Northern Ireland to commemorate the event, which takes place despite the Stormont Assembly, key to the deal, still not sitting.
The peace brought by the deal also remains fragile, with the terrorist threat having been raised amid warnings of possible attacks on police.
Mr Sunak said there is a need to "recommit to redoubling our efforts" to deliver on the promise made when the deal was signed on 10 April 1998.
Reflecting on the "beginning of a new chapter," Mr Sunak said the agreement "continues to enjoy huge international support," as demonstrated by Mr Biden's visit.
"As we look forward, we will celebrate those who took difficult decisions, accepted compromise and showed leadership, bravery, perseverance, and political imagination.
"We commemorate those who are no longer with us and the many who lost their lives by trying to prevent violence and protect the innocent.
"And we give thanks to them as we reflect on the new generations that have grown up and continue to grow in a world in which peace and prosperity has prevailed.
"While it is time to reflect on the solid progress we have made together, we must also recommit to redoubling our efforts on the promise made in 1998 and the agreements that followed," he said.
That vision, he said, is of "economic opportunity, prosperity and stability".
"So we must get on with the business of governance.
"My mission, duty and responsibility as Prime Minister of the United Kingdom is to deliver for people in Northern Ireland.
"We stand ready to work with our partners in the Irish Government and the local parties to ensure that the institutions are up and running again as soon as possible.
"There is work to be done," Mr Sunak said.
The Police Service of Northern Ireland has warned of the potential of dissident republicans launching attacks on police officers in Derry today, Easter Monday.
MI5 recently raised the terrorism threat level in Northern Ireland to severe, meaning an attack is highly likely.
Jeffrey Donaldson, leader of the Democratic Unionist Party, has insisted the political vacuum in Northern Ireland caused by his party's refusal to re-enter Stormont is not to blame.
In February last year the DUP withdrew its support for the power-sharing institutions formed by the Good Friday Agreement as it protests against post-Brexit trading arrangements.
Mr Sunak will meet Mr Biden off Air Force One when he arrives tomorrow evening.
The president will take part in events on Wednesday, before heading to Ireland, where he will visit counties Dublin, Louth and Mayo.
Yesterday, Taoiseach Leo Varadkar echoed Mr Sunak's sentiments.
Mr Varadkar said that he will be intensifying contact with Mr Sunak in the coming weeks to try to restore the institutions in Northern Ireland.
"We're working towards having the institutions up and running in the next few months," he told RTÉ's This Week programme.
Additional reporting PA
