Ian Paisley and Martin McGuinness, once the bitterest of foes, yesterday pledged to put hatred in the past and work together for a "new beginning" for Northern Ireland.

On a historic occasion marked by smiles, handshakes, poignant words and cheerful optimism, the 81-year-old leader of the Democratic Unionist Party and the 56-year-old chief negotiator of Sinn Fein were sworn in as First Minister and Deputy First Minister respectively to lead Stormont's new power-sharing executive.

As some 300 guests gathered in the assembly's Great Hall, Mr Paisley remembered the victims of the Troubles and recognised how, in politics, no-one got everything they wanted but that the Unionists had secured enough from Republicans to move on and make progress.

"Northern Ireland has come to a time of peace, a time when hate will no longer rule.

"How good it will be to be part of a wonderful healing in our province. Today, we have begun to plant and we await the harvest," declared the MP for North Antrim.

Mr McGuinness, who insisted yesterday was about "not hype but history", said the road ahead would have many "twists and turns" but he spoke about moving into "a new political era based on peace and reconciliation".

This sentiment was echoed by Bertie Ahern, the Taoiseach, who called for "a new era of mutual respect and peace".

The dramatic day delivered Tony Blair, beleaguered on much of the political agenda, his greatest domestic triumph and will, as he contemplates his resignation statement tomorrow, form a key part of his legacy.

The Prime Minister sought to place yesterday's breakthrough in context, stressing how Northern Ireland's new dispensation gave its people the chance to "shake off those heavy chains of history".

He said: "Northern Ireland was synonymous with conflict.

It was felt intractable; the Troubles not so much a dispute as a fact of life, irreconcilable differ- ences.

"People felt it could not be done, even sometimes that it shouldn't be done; the compromises were too ugly.

"Yet, in the end," he insisted, "it was done and this holds a lesson for conflict everywhere: to define the right political framework since only through politics can come peace that lasts; to get the external forces, especially the governments, working in alignment with those internal forces striving for peace."

He added: "But, above all, to persevere, never to give up, never to accept that the true will of the people is conflict when they are given the chance to live in peace."

Mr Paisley's DUP has four ministers in the new executive, covering the portfolios of finance, the economy, environment and culture, while Sinn Fein has three, covering education, agriculture and regional development.

The Ulster Unionists secured the posts of health and employment, while the nationalist SDLP got social develop-ment.

The DUP's Ian Paisley Jr and Sinn Fein's Gerry Kelly will be junior ministers, working in the office of the First and Deputy First Ministers.

Their elevation to high office was witnessed by a distinguished list of politicians from both sides of the Atlantic.

Senator Edward Kennedy rubbed shoulders with for- mer Irish Taoiseach Albert Reynolds and Home Secretary John Reid in the public gallery.

Elsewhere, Gordon Brown set out what he said was the unique package under which he would provide at least £51.5bn for Northern Ireland over the next decade or so.

The Chancellor said he looked forward to working with the new executive to "create a dynamic Northern Ireland economy and world-class public services for all and together with the Irish government to create a strong all of Ireland economy".

Yesterday's dramatic events were the culmination of a long and arduous road since the 1998 Belfast Agreement, which began the process of putting behind Northern Ireland its troubled past, that claimed the lives of 3600 people.

Tributes poured in from abroad. US President George W Bush applauded the people of Northern Ireland for their "desire to overcome a history of violence and division".

Germany, which holds the EU presidency, said the new power-sharing deal gave "hope and optimism to all those in other parts of the world working for the peaceful resolution of conflicts".

Sandwiched in between the formal oaths and speeches was a set-piece television moment when the leading players sat on the sofa in Mr Paisley's new office, chatting, joking and taking tea.

Referring to Mr Blair's imminent departure from Downing Street, the new First Minister said to laughter all around: "As you're going out as a young man, I'm coming in as a granddad."

However, once the congratulatory glow of yesterday's genial occasion is over, ministers on both sides of the political divide will face tough battles as they struggle to make sharing power work for all the people of Northern Ireland.