It is a cynical PR stunt designed to make the IRA and the republican movement look good

Nigel Dodds, DUP

But it later withdrew what it described as an "historic" offer after unionists rejected a report by the head of the commission, Canadian General John de Chastelain.

His analysis that the IRA had entered into a decommissioning process was rejected by the Ulster Unionist Party and DUP because no timescale was agreed.

The UK Government accused the IRA of playing into the hands of sceptics of the peace process by the withdrawal.

Colombia arrests

In the latest statement, the IRA said political progress would be directly influenced by the attitude of other parties and the British Government to its latest move.

The statement added: "The IRA's commitment is without question.

"However, as we have said before, peace making and peace keeping is a collective effort.

General de Chastelain: Confirmed method

"It is our considered view that the Irish peace process can succeed."

The arrest of three IRA suspects in Colombia accused of handling drugs and explosives has also added to the sense of crisis in the peace process.

In its statement the IRA said there had been "a lot of ill-founded and mischievous speculation" about the arrests of James Monaghan, Martin McCauley and Niall Connolly.

"We wish to make it clear that the Army Council sent no-one to Colombia to train or to engage in any military cooperation with any group," it said.

On Wednesday, UK Prime Minister Tony Blair and Irish counterpart Bertie Ahern reaffirmed their commitment to the package of proposals aimed at breaking the impasse, which was put to the parties following talks in Staffordshire in July.

A spokesman for the Irish Government said it looked forward to an early and comprehensive resolution of the arms issue following the latest move by the IRA.

'Panic'

But the IRA statement was branded "nauseating" by Democratic Unionist Party MP Nigel Dodds.

"It is a cynical PR stunt designed to make the IRA and the republican movement look good as we run up to the weekend and as the international community focuses in the actions of terrorists," said Mr Dodds.

He also claimed that the IRA's message of sympathy to the victims of the US terror attacks was hypocritical.

A spokesman for the Ulster Unionist Party repeated warnings that the IRA would face further penalties if they did not begin emptying their arms dumps.

He also accused the IRA of lying over the arrests in Colombia and their links to the Farc rebels.

"The IRA denials over Colombia are clear evidence of panic in their ranks at the international backlash against terrorism," he said.

Deal deadline

Chairman of the nationalist SDLP, Alex Attwood, said all paramilitaries would be judged on "actual progress on the putting of weapons completely and verifiably beyond use".

Under the current legislation, Northern Ireland Secretary John Reid created another six-week period during which the parties could come to agreement on the issues blocking the political process - policing, IRA decommissioning and British government demilitarisation.

If the parties do not reach a deal by 22 September, Dr Reid could opt for an open-ended suspension of the institutions followed by a review, or for a second short suspension of the assembly.

Either option would avoid the total collapse of the Stormont government.