Northern Ireland's First Minister David Trimble has called on republican paramilitaries to begin decommissioning in the next few weeks.

Mr Trimble was speaking following a meeting at Downing Street with the Prime Minister, Tony Blair, to bring him up to date on the latest political developments in the province.

The first minister, who also leads the Ulster Unionist Party, said the onus was now on paramilitary groups to take the peace process forward.

He said: "In the course of the meeting we reviewed a wide range of issues.

"The focus was on political development in Northern Ireland.

"We were able to report to him much progress had been made by the Ulster Unionist Party and others in that we have now done everything we can do and need to do in terms of implementing the agreement.

"Then we discussed the prospect of implementing the final stage of the agreement.

"Of course onus for that lies exclusively with the paramilitaries, in particular with the republican movement."

Power was devolved to the Northern Ireland Assembly last month after the Ulster Unionist Council backed the peace deal brokered by former US Senator George Mitchell.

It allowed the Ulster Unionist Party to enter into government with Sinn Fein before the handover of terrorist weapons but also set a deadline of February for Mr Trimble to decide whether there had been enough progress made in decommissioning to continue supporting devolution.

The latest report from the international body on decommissioning is due later this month and Mr Trimble said he would like to see progress by the paramilitaries before then.

He said: "We call upon the republican movement to implement the agreement and the understandings in Mitchell [review] and to produce the necessary progress in January.

"If that is done then there will be no need for anyone to whinge about February.

"If there is no progress in decommissioning then there is default in terms of implementing the Mitchell review and the agreement.

"We know the situation we will then be faced with."

But Sinn Fein President Gerry Adams has warned that ultimatums will not work in relation to IRA disarmament.

Speaking after a 45-minute meeting in Washington with US President Bill Clinton, Mr Adams called on Mr Trimble to "be leaderly" in helping to move the peace process forward.