The first republican to lead Northern Ireland’s devolved government vowed to work together with British and unionist colleagues as she took up her role.
Michelle O’Neill pledged: “I will serve everyone equally and be a first minister for all.”
The devolved administration in Stormont has resumed following a two-year break, after unionist party the DUP agreed to a new post-Brexit deal designed to end trade borders between Northern Ireland and the rest of the UK.
DUP politician Emma Little-Pengelly was nominated as deputy first minister under power-sharing arrangements.
Ms O’Neill, 47, is vice-president of Sinn Fein, which believes Northern Ireland should leave the UK. The party was also associated with the IRA, which carried out a terror campaign until the Good Friday peace agreement in 1998.
Her elevation to first minister follows Sinn Fein becoming the region’s largest political party in the 2022 Assembly election.
Highlighting her commitment to the peace deal, she said: “I stand here proud, elected first minister as someone who represents the Good Friday generation, and someone who will lead us into the next 25 years. I am sorry for all the lives lost during the conflict, without exception. As first minister I am wholeheartedly committed to continuing the work of reconciliation between all of our people.
“As an Irish republican I pledge co-operation and genuine honest effort with those colleagues who are British, of a unionist tradition and who cherish the Union.”
Northern Ireland Secretary Chris Heaton-Harris said that the resumption of devolved government strengthened the province’s place in the UK.
He said: “Yesterday we saw Northern Ireland politicians returning to govern for the people that elected them. It’s a deal that firmly enshrines Northern Ireland’s place in the Union and in the UK Internal Market in law.
“It’s a deal that prevents future governments from agreeing any new areas of EU alignment for Northern Ireland that would damage its place in our market.”
Last week the Government fast-tracked two pieces of legislation through the House of Commons to put the new trade arrangements in place and open the way for the Assembly to return. Key among the priorities for new ministers will be dealing with a budget crisis.
The UK Government has offered a £3.3billion package to secure the region’s finances, which includes £600million to settle public sector pay claims.
Mr Heaton-Harris said the new trade arrangements would benefit the economy and could lead to lower prices in the high street.
He said: “We have expanded the range of goods within our UK Internal Market system, meaning millions more products can move each year and Northern Ireland will be able to import agrifoods based on UK and not EU tariffs.”
Ms Little-Pengelly also called for unity in her speech, saying: “We are all born equal and the people who look on this sitting today demand us to work together.”
Irish President Michael D Higgins praised the speeches as “impressive in their inclusion and warmth”.
But Sir Robert Buckland, chair of the Commons Northern Ireland Committee, said: “Bold policymaking will be required to make good struggling public services, resolve the ongoing pay dispute and tackle continued paramilitary activity.”