Mr Trimble wants a clear and unambiguous statement of the organisation's intentions as the decommissioning of weapons process gets underway.

IRA under new pressure

He has asked US President Bill Clinton to raise the issue with Gerry Adams when the pair meet in Washington this week during the Sinn Fein president's visit to the US.

Mr Trimble said: "We want Sinn Fein-IRA to declare that the terrorist campaign is over and that there will be no resort to violence by any element of the organisation in the future."

Sinn Fein is understood to have met the head of the decommissioning body General John De Chastelain earlier this week.

Mr Trimble said: "I hope that further steps like this will follow.

"Sinn Fein-IRA must face up to the need to decommission and give practical effect to the Mitchell Principles and the Agreement itself.

No justification for IRA to keep its weapons

"There is no support or justification for Sinn Fein-IRA retaining their weapons and Semtex and they should now follow the example of others who have nominated representatives to the decommissioning panel."

Arms experts say the IRA has two to three tonnes of Semtex explosive, two or three ground-to-air missiles and hundreds of AK-47 assault rifles and other guns.

It is also believed that the Ulster Defence Association gunmen have at least 200 rifles or machine pistols, at least 200 handguns and an unknown amount of commercial explosive. The Ulster Volunteer Force is said to have a similar cache.