The government has repeated its demand for the IRA to decommission its weapons.

As the prime minister met Ulster Unionist leader David Trimble on Tuesday, Number 10 stepped up its pressure on the province's political parties with a warning that May's local elections meant there was a deadline for progress to be made.

Number 10 refused to confirm or deny that it had received positive signs from the IRA leadership over a move to decommission the rest of its arms, but officials signalled its determination to see progress.

Tony Blair's speech in Ulster last autumn is being used as the starting point.

"It's all there set out in black and white. Paramilitary activity has now become completely counter-productive," said Downing Street.

Ulster's political parties had been given a "period to reflect" which was "now coming to a natural end".

There was a warning to all sides that because of the local elections deadline, time was now running out.

"We are facing a relatively short window of opportunity. But it's there and the prime minister believes we should all seize it," said the official spokesman.

Insiders are predicting that the week leading up to the St Patrick's Day celebrations in March will see the final decision taken on whether the assembly elections will be postponed - a move which would require legislation.

Northern Ireland secretary Paul Murphy is thought to be pessimistic that a deal to end the present deadlock and restore the devolved assembly is achievable.

Tony Blair is set for a round of meetings this week with the province's political leaders, including the SDLP and Sinn Fein.

After an hour-long meeting with the prime minister, UUP leader David Trimble said it was "increasingly problematic" that the elections would be able to go ahead.

The party also demanded that the IRA disband and end "all violent and illegal activities".

Former Stormont UUP minister Michael McGimpsey called for "an end to paramilitarism in all its forms".

"That covers a broad and extensive menu from the IRA ending so-called punishment beatings and shootings to stopping the importation of weapons, intelligence gathering and targeting. It must also fulfil its obligations under the Belfast Agreement on decommissioning."

McGimpsey also slammed loyalist paramilitaries who are currently locked in a bloody internal feud.

"Loyalists also need to honour their obligations because we have had Sinn Fein hiding behind UDA actions and loyalists hiding behind the IRA," he said.