Mr Blair said he hoped all unionists would welcome the body

The government confirmed the identities of all four members to the body on Thursday and made it clear that only British nominees to the panel will consider the internal matters related to the Stormont Assembly.

The commission will report on the IRA and loyalist ceasefires every six months and scrutinise the government's programme of demilitarisation and complaints about political tactics which threaten the stability of the devolved institutions.

The four-member body will comprise of Richard Kerr, a former deputy director of the Central Intelligence Agency, Commander John Grieve, former head of the Metropolitan Police's anti-terrorist squad, Stormont Speaker Lord Alderdice and retired Irish civil servant Joe Brosnan.

However, only the British Government's nominees - Lord Alderdice and John Grieve - will examine how devolved ministers and Northern Ireland parties are honouring their commitments under the Good Friday Agreement.

We have three persons who have particular experience in dealing with paramilitary related problems David Trimble UUP leader

Ulster Unionist leader David Trimble welcomed the announcement as a positive step.

"With regard to the personnel, the people who are going to carry out this monitoring function, I would hope that people would be generally encouraged by it," he said.

"We have three persons who have particular experience in dealing with paramilitary related problems such as violence and terrorism."

However, speaking in Dublin, the Sinn Fein President, Gerry Adams, said his party would not co operate with the new body.

"We are against the commission, it gives to a British minister a power which he didn't have and doesn't have under the Agreement," he said.

A spokesperson for the anti-Agreement Democratic Unionist Party DUP doubted whether the body would be either independent or effective.

SDLP leader Mark Durkan said the commission would raise more questions than answers.

"It is a bit of a mish-mash," he said.

Paul Murphy revealed details of the commission's role

"We have here, I think, a ramshackle construct which will probably just about stand if nobody tries to lean on it.

"Once anybody tries to lean on it, and particularly if people try to lean on it from different directions, I think it gets into bother," he said.

Meanwhile, Northern Ireland Secretary Paul Murphy said the establishment of the commission was a crucial element in London and Dublin's plan for restoring devolution at Stormont, which has been suspended since last October.

He said: "I believe that it will play a valuable role in helping to provide assurance that the necessary moves towards a genuinely peaceful and democratic society with stable devolved government that we want to see are real and permanent."

Mr Murphy said the government hoped to pass the necessary legislation at Westminster as soon as possible.

The commission has been a source of controversy for the Ulster Unionist Party, with a number of prominent members voicing concern over the role of the Irish Government's nominee.

Mr Murphy said the commission would assess whether paramilitary leaders are directing such activities or trying to prevent them.

Lord Alderdice is thought to be the body's NI member

The commission will also be asked to assess how the government is honouring its commitment to scale down military installations, and if it is meeting agreed timescales.

In particular, commission members will examine the demolition of Army towers and observation posts in Northern Ireland, the withdrawal of troops and the closure and dismantling of military bases and installations.

A report will be prepared on the government's security normalisation programme.

The commission will report their findings solely to the British Government and recommend what measures, if any, should be taken by the Northern Ireland Assembly.

The commission arose out of discussions on the joint declaration earlier this year involving London and Dublin and the political parties.

It formed part of a side deal between the two governments, stemming from demands by the Ulster Unionist Party for effective sanctions against those who breach the Agreement.

Published in May, the joint declaration outlined plans to reduce troop numbers to 5,000 as part of an attempt to move the Northern Ireland political process forward.