Republican and nationalist politicians have reacted with incredulity and anger to the decision to suspend Northern Ireland's nine-week-old power-sharing executive.

Northern Ireland Secretary Peter Mandelson re-imposed direct rule as General De Chastelain's long awaited report on progress on the arms issue was published. Sinn Fein leader Gerry Adams accused Mr Mandelson of re-imposing direct rule under threat from the Ulster Unionist Party and in full knowledge of what he described as "a major breakthrough" on the arms issue.

"It's quite bizarre that a British secretary of state, is order to catch a six o'clock deadline, would move to a unionist threat," he said.

The deputy first minister of Northern Ireland's suspended power-sharing executive said re-imposition of direct rule would be greeted with "incredulity" by most nationalists.

Seamus Mallon, the deputy leader of the nationalist Social Democratic and Labour Party (SDLP), said it would be "very, very difficult" to rebuild the institutions of devolved government.

"Why were institutions which were working well suspended in relation to this or any other issue?" he asked. He described as a "mistake" the decision to suspend the executive.

"I think it was unwise of him (Mr Mandelson) and it would have been unwise of them (the Ulster Unionists) to ask him," he said.

Unionist politicians have welcomed the suspension of the institutions but said they took no pleasure from the decision.

Ulster Unionist leader David Trimble said: "The background to this was our decision at the end of November to jump first in the expectation that the republican movement would reciprocate.

"When it became clear that the republicans had failed to jump then our position became impossible".

Later, a Ulster Unionist colleague said the party was looking forward to the forthcoming review.

Michael McGimpsey, minister of arts and culture in the suspended executive, said it was inevitable that the political process would eventually work.

"You have to persevere - and when you're dealing with organisations such as the republican movement you have to be very stubborn and you have to in effect never give up.

"We will not be letting them off any of the hooks," he said. "They are in a process and decommissioning is the inevitable outcome of the process they're on.

'Disappointed'

"We're going to ensure that they deliver for the people of Northern Ireland and for the people of Ireland in general."

The anti-Agreement Democratic Unionist Party accused the Ulster Unionists of betraying their electorate by acting outside their party's manifesto.

Nigel Dodds, who was a member of the Northern Ireland executive, accused the party of making concessions to the IRA and getting nothing in return.

He said it was now clear that the UUP had made an error of judgement. "The leadership trusted the IRA despite clear warnings of the danger of yet more concessions to republicanism," he said

The Irish government is reported to be "disappointed" by the latest developments.