Every effort must be made to put the Good Friday Agreement "back together again", the prime minister has said.

Tony Blair told the Commons on Wednesday that "we have reached the crunch point - where people have got to decide whether they are committed to exclusively peaceful means or not".

The power-sharing executive was suspended for the fourth time at midnight on Monday following allegations of IRA intelligence gathering in the Northern Ireland Office.

Four people have been charged over the claims.

Ian Paisley: To lead a DUP delegation to meet Tony Blair

Addressing the political impasse in Northern Ireland during Question Time in parliament, Mr Blair said: "There are two reasons we took the decision we did (suspending devolution).

"The first reason is that to have said that the IRA have come off ceasefire would be a very, very serious thing to do," he said.

"We had to weigh, very seriously, the consequences of that. The second thing is that frankly, without the support of the nationalist community as well the exclusion motion would not have succeeded - so we would have been back in suspension in any event."

'Fresh elections'

Mr Blair said he did not want suspension to last.

"I think that it is worth every effort to try and secure a way of putting the Agreement back together again and moving it forward," he told MPs.

Later on Wednesday, the Democratic Unionist Party met the prime minister and the secretary of state to discuss the political crisis.

The DUP again called for a renegotiation of the Good Friday Agreement and fresh assembly elections.

Following 45 minutes of talks, Mr Paisley said: "It is the onus and duty on the prime minister of this country to see that no terrorist organisation gets into the heart of government of any part of this United Kingdom. That is the issue.

"At the moment he has not been prepared to face up to the IRA, he has backed off from facing up to them."

Speaking in County Armagh on Wednesday, Sinn Fein president Gerry Adams said Mr Blair should set up round-table talks immediately.

"To many people it appears that there is a tolerance within the British system of the armed actions of unionist paramilitaries.

"The British Government is not the referee in this process. I do believe that the British prime minister has played a positive role but now is not the time to slip into a single item agenda," he said.

"The mistake is suspending the institutions should not be compounded."

Meanwhile, other talks are expected to take place behind the scene between politicians and officials in an attempt to restore confidence in the political process.

On Tuesday, the Northern Ireland Secretary, John Reid said the suspension of the assembly would create "a breathing space" that will allow the peace process to move forward.

NIO ministerial responsibility

NI Secretary John Reid - Overall responsibility Minister of State Jane Kennedy - Security, Education, Employment and learning Des Browne - Health, Equality, Human Rights, Community relations Ian Pearson - Finance, Economy, Agriculture Angela Smith - Environment, Regional Development, Culture and Arts

He also outlined the portfolios that have been given to the new Northern Ireland Office ministers MPs Angela Smith and Ian Pearson.

And he told MPs that elections to the Assembly next May would go ahead as planned.

Meanwhile, Irish Premier Bertie Ahern has told the Dail that the republican movement needs to move more quickly from paramiltiarism to normal constitutional politics.

Earlier on Tuesday, Sinn Fein President Gerry Adams challenged the British and Irish governments to spell out how they intend to implement the Good Friday Agreement.

Also on Tuesday, a leading clergy man called for the IRA to say the war was over for good as a first step towards rebuilding the trust needed to revive the Northern Ireland political process.

John Reid: Government is fully committed to Agreement

Church of Ireland Primate Archbishop Robin Eames said it was time for loyalist and republican paramilitaries to announce the threat of violence was lifted.

Earlier this month, Mr Trimble said his party would pull out of power sharing unless the UK Government proposed the expulsion of Sinn Fein from the Stormont administration.

Unionists demanded Sinn Fein's expulsion from government over allegations of IRA activity, including claims it was involved in training left-wing Colombian guerrillas and was behind a break-in at the police's Belfast headquarters in March.