The British Prime Minister, Mr Tony Blair, was under renewed Conservative pressure to reassess the status of the IRA's ceasefire following yesterday's revelations about republican intelligence-gathering activity.
Conservative Central Office was last night awaiting details from the Home Office about the precise number of senior Tories featured on the list, discovered by the Police Service of Northern Ireland, which also included details about loyalist leaders and a number of British military establishments.
The Conservative leader, Mr Iain Duncan Smith, said he was "deeply, deeply concerned". He and Northern Ireland's First Minister and Ulster Unionist leader, Mr David Trimble, were thought likely to raise the discovery directly with Mr Blair.
Ulster Unionist sources said a decision on whether to seek a meeting with Mr Blair would be taken after discussions with the acting Chief Constable, Mr Colin Cramphorn, on Monday.
The Tory temper was reflected by the shadow Northern Ireland spokesman, Mr Quentin Davies, who said the revelation raised "very serious question marks about the nature of the IRA ceasefire and the Prime Minister's assessment of its current status".