Calling it the beginning of a new era in the troubled British territory, leaders from Protestant and Catholicparties pledged on Tuesday to share powerin a new administration for Northern Ireland.

Ian Paisley, 81, leader of the Protestant Democratic Unionist Party, and Martin McGuiness, 56, deputy leader of Sinn Fein, were sworn in to lead a 12-member cabinet to govern Northern Ireland in peace.

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Ian Paisley, leader of the Democratic Unionist Party, arriving at Stormont Parliamentary Building in Belfast Northern Ireland on Tuesday, has been elected first minister in a 12-member cabinet. ((Peter Morrison/Associated Press))

With British Prime Minister Tony Blair and Ireland's Prime Minister Bertie Ahern in Belfast to watch, Paisleywas electedfirst minister, followed by McGuiness as deputy first minister.

The two men, described as "sworn and bitter enemies" by Northern Ireland Secretary Peter Hain,swore on Tuesdayto co-operate with each other and with the neighbouring Republic of Ireland.

The oath requires all government ministers "to uphold the rule of law based as it is on the fundamental principles of fairness, impartiality and democratic accountability, including support for policing and the courts."

Paisley has said that co-operation with Catholics would be tantamount to surrender, while the IRA had long refused to accept the British courts.

Immediately afterthe two leaders were installed,the 12 positionsin the power-sharing cabinet were filled on the basis of how many seats each party holds in the Northern Ireland Assembly.

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Martin McGuinness, deputy leader of Sinn Fein, is the new deputy first minister in Northern Ireland's cabinet. ((Peter Morrison/Associated Press))

Paisley's Democratic Unionists took five cabinet positions, while Sinn Fein took four. The moderate Protestants of the Ulster Unionists were assigned two, while the moderate Catholics of the Social Democratic and Labour Party were given one.

Power-sharing was a central goal of the U.S.-brokered Good Friday peace accord of 1998, but Blair and Ahern since have had to lead several summits aimed at coaxing local leaders of the British Protestant majority and Irish Catholic minority together.

A four-party coalition led by moderate Protestants and Catholics took power in December 1999, but repeatedly broke down amid confrontations between Protestants and Sinn Fein. It collapsed for good in October 2002 over allegations that the IRA was using Sinn Fein's position inside government to pilfer files and other intelligence on potential targets.

'One of the mightiest leaps forward'

Ahead of Tuesday's ceremony, McGuiness saiditwould bea historic moment for Northern Ireland.

"What we're going to see today is one of the mightiest leaps forward that this process has seen in almost 15 years," he said.

The process, shepherded partly by retired Canadian judge Peter Cory and retired Canadian general John de Chastelain, will restore home rule to Northern Ireland.

The Northern Ireland executive will have control over local affairs, while Britain retains sovereignty over the territory.

Paisley called it the beginning of a new era for Northern Ireland.

"And I believe we're starting on a road which will bring us back to peace and prosperity," he said.

Hain, the United Kingdom's minister responsible for Northern Ireland, said he was astounded that Paisley and McGuiness have been able to move beyond the past to focus on a new future.

"That's what fills me with optimism as well," Hain said. "Not just that the darkness and horror of the past is now behind us, but that there is a real prospect of this government working.

"I think it will become increasingly difficult for the sectarianism and bigotry underneath all of this to flourish," he said.

About 3,700 people have been killed infour decades ofsectarian violence Northern Ireland.

Paisley and McGuiness have both served time in jail for their roles in that bloody history.

Paisley, a bombastic orator who leads his own anti-Catholic church, went to prison in 1969 for organizing an illegal demonstration against Catholic marchers fighting for equal rights in voting, housing and employment.

McGuiness, a high school dropout who became an IRA commander, went to prison in the 1970s for his membership in the IRA. He also served in the IRA's ruling army council, a committee that oversaw the killing of thousands in the struggle for control of Northern Ireland.

Mark Carruthers, a journalist with BBC Northern Ireland,told CBC News on Tuesdaythe ceremony that brought together Paisley and McGuiness was astonishing because the two used to be such bitter political enemies. It took place in Stormont, home of the Northern Ireland Assembly.

"It was remarkable to see them standing together on the steps of Stormont, remarkable to see the proceedings whereby they were elected to these new positions of first minister and deputy first minister in the chamber itself, without any hullabaloo, without any fuss, without any dissenting voices," he said.

"And already, they have got down to the business of government."

With files from the Associated Press