Ministers of Northern Ireland's rival parties were sworn in to office Tuesday, marking the restoration of a power-sharing government in the previously conflict-ravaged province.

Ian Paisley, leader of the Democratic Unionist Party (DUP), the largest party in the province, was sworn in as Northern Ireland's First Minister at Stormont, the seat of its parliament, in Belfast.

Sinn Fein's Martin McGuinness became his First Deputy.

British Prime Minister Tony Blair and his Irish counterpart Bertie Ahern were present to witness the revival of the 108-seat Northern Ireland Assembly, along with dignitaries from the United States and some European countries.

"Today, at long last we are starting upon the road which leads to lasting peace. I believe Northern Ireland has come to a time of peace," said Paisley at the ceremony marking the return of devolution to Northern Ireland.

In a speech, the leader, who is now over 80, also paid tribute to all those who had given their lives to peace in the province.

McGuinness welcomed all friends from across the world who were present to mark the restoration of devolution.

McGuinness also pledged that the government was determined to seek a "better future" for all in the province and to bid farewell to the "painful past."

Blair hailed both parties, the DUP and Sinn Fein, as being "committed to sharing power and securing peace" in Northern Ireland, adding that they "hold a lesson for conflicts everywhere" showing that only politics is the final resolution.

Ahern called the event "a historical beginning of a new era."

"Conflict is not inevitable," he said, urging the coalition government to "take on the duties and responsibilities" and "shape a future in a new and better way."

Meanwhile, dozens of hard-core protesters as well as demonstrators unhappy about Blair's Iraq policy rallied outside the parliament building.

Over the past years, Blair and Ahern have made constant efforts in bringing peace to Northern Ireland. The ceremony of revived devolution is widely regarded as Blair's major legacy as he plans to announce his departure from office this week.

The first meeting of the new power-sharing executive is due later this week.

With the devolution government now restored, direct rule over Northern Ireland by Westminster will officially end at midnight Tuesday, almost five years since it was suspended in 2002 following allegations of intelligence gathering within Stormont.