The Ulster Unionist leader has repeated his challenge to republicans to commit to the democratic process in Northern Ireland by disarming.

Speaking to the BBC's Breakfast with Frost programme David Trimble repeated his position outlined after meeting his party's 860-member ruling council on Saturday, that he could not again form a devolved government with Sinn Fein without "unambiguous" moves towards IRA decommissioning.

He said that he hoped a way could be found through a speedy review of the peace process for reviving the administration suspended by the Northern Ireland Secretary on Friday because of the arms impasse.

But he said it was now "make your mind up time for the whole of the republican movement" and that the "ball is still definitely in their court".

"It is a matter for Sinn Fein to decide whether they are really going to commit themselves to politics. They have tried to get through the last number of years keeping both options, both politics and terrorism open but you can't proceed that way," he said.

"We are in a really frustrating situation here that the hopes of the whole community are being held up by a handful of men, about 200 people who are keeping everything back simply because they want to keep the terrorist option open."

'UUP now sceptical'

The First Minister of the suspended assembly also warned that having taken a risk by forming the power-sharing executive with Sinn Fein in December his party would now be much more "sceptical" of any other ambiguous statements or "nods and winks" offered by republicans as assurances.

He said that although Sinn Fein President Gerry Adams and Martin McGuinness had contacted him before the assembly suspension on Friday to tell him about a new IRA move, which was formed the basis of a second report by the international decommissioning body "neither Mr Adams or Mr McGuinness could tell me what it was".

Mr Trimble rejected republican accusations that he has caused a crisis in the peace process precipitating suspension of the institutions by creating a deadline of 31 January for IRA decommissioning, not contained in the Good Friday Agreement.

The deadline date of the first report on decommissioning by General de Chastelain was a clearly recognised following last year's Mitchell review of the peace process.

Mr Trimble did not say that IRA weapons decommissioning must actually start before his party would be prepared to re-enter the assembly.

But he said he still expected decommissioning by 22 May 2000 as outlined in the agreement.

The Ulster Unionist leader was speaking after his party agreed on Saturday to set up a broadly based working group to consider the issues the party would be focusing on going into a new review of the peace process.

'Breakthrough ignored'

But Sinn Fein has rejected the Ulster Unionist and British government view that the 11th hour move by the IRA was ambiguous and contained no new initiative.

The IRA told the de Chastelain Commission it would consider how to put guns and explosives beyond use if the causes of conflict were removed.

The general reported: "The Commission believes that this commitment¿holds out the real prospect of an agreement which would enable it to fulfil the substance of its mandate."

Sinn Fein's Health minister in the suspended executive Bairbre de Brun said the assembly suspension was a disaster and that the arms issue was a matter solely for the de Chastelain Commission to resolve.

Speaking to Sky News she said: "As a politician I gave the responsibility to deal with that to General de Chastelain. General de Chastelain has said he feels he can carry out his remit. It's not up to me, you or David Trimble to do his job for him."

At a news conference on Saturday Gerry Adams said London and Dublin knew of the "major breakthrough" hours before Mr Mandelson suspended the 10-week-old parliament.

The assembly suspension prevented David Trimble having to honour a commitment to his party to resign if the IRA had not started to decommission by 31 January.

He added there was anger in the nationalist and republican community at the way the Ulster Unionists had dictated events and the government had caved into their agenda.

"Even if we had delivered the IRA lock, stock and barrel in a way which British militarism could not in 30 years, it would not have been enough yesterday because the whole project was about what was going on within unionism," he said.

The Sinn Fein leader did not confirm whether his party would participate in any review of the peace process, saying a meeting of its ruling council would take place next week to discuss the issue.