Ministers from both sides of the border are to convene for the first meeting of the North South Ministerial Council in almost three years.
The meeting will be the last major political engagement for Leo Varadkar as Taoiseach.
The gathering in Armagh comes hours before he formally resigns as premier when he meets President Michael D Higgins in Dublin on Monday evening.
His successor as Fine Gael leader, Simon Harris, will also be at the council in one of his final jobs as Dublin’s higher education minister before his expected election as Taoiseach in the Dáil on Tuesday.
The council is the primary north-south political body established under the Good Friday Agreement.
It was unable to function during the two-year political impasse at Stormont, but the restoration of devolution earlier this year enabled its reactivation.
The last meeting was a virtual one held during the Covid pandemic in 2021.
The last in-person meeting of the council was in July 2020.
The meeting in Armagh will be chaired by Stormont First Minister Michelle O’Neill and deputy First Minister Emma Little Pengelly.
Discussions are set to focus on trade and business issues and investment in areas of mutual interest.
Mr Varadkar said it was an honour to end his tenure as Taoiseach by attending the council.
“This plenary meeting of the North South Ministerial Council is a really significant and positive moment for the island of Ireland,” he said.
“It’s an honour to lead the Irish delegation of ministers to meet with our Northern Ireland Executive counterparts in my last major engagement as Taoiseach.
“Many of the challenges facing the world today are shared across the island, whether climate change, energy security, good jobs, and ensuring that our workforces have the skills they need for the future.
“I will also take this opportunity to wish the First Minister and deputy First Minister well in their roles to achieve the best for all the people of Northern Ireland.
“We are working with the Executive to build on the peace and prosperity of the last 26 years to make sure it is shared by all.”
