The British government and the Conservative leadership last night appeared to have contained the controversy over the compilation of a so-called IRA "hit list" of senior Tory politicians.
At the same time it became clear that there was growing alarm in Whitehall at the leaking of highly sensitive information from within the British political or security system in the run-up to the imminent Irish election.
At a meeting at 10 Downing Street, the Conservative leader, Mr Iain Duncan Smith, again declared himself "deeply concerned" about continuing republican intelligence-gathering activities and urged the Prime Minister, Mr Tony Blair, to consider "sanctions" against Sinn Féin.
However, it is understood the Tory leader was unspecific as to what action the British government might take. Mr Blair in turn sought to assure him there was no evidence of a threatened resumption of the IRA campaign, nor any reason to believe that the recently discovered list - including details of senior Conservative politicians and British military establishments - was "active."
Speaking after their 30-minute meeting, Mr Duncan Smith said Mr Blair had assured him the government viewed the discovery of the list with "the utmost seriousness" and would "continue to look into the matter directly."
That was echoed by Dr John Reid, the Northern Ireland Secretary, who said the government took these matters very seriously, while stressing that no one should "rush to judgment" on the basis of speculation.
"The information I have is that there has been no enhanced threat to any individual politician at Westminster in any party. That is the security assessment I have received. In this case the assessment was there was no increased threat. We assess there is no threat to the ceasefire," he said.
However, pressure remained on Mr Blair last night as a fresh controversy threatened over Sinn Féin facilities at Westminster and ahead of Mr David Trimble's meeting with Mr Blair, either later today or tomorrow.
While yesterday's meeting between Mr Blair and Mr Duncan Smith concentrated on the discovery of the IRA list, the Prime Minister's talks with the First Minister are almost certain to focus on the continuing investigations into the St Patrick's Day break-in at the Castlereagh police complex.
Pending a final determination on that, Mr Trimble appears to be resisting internal party pressure to impose fresh sanctions against Sinn Féin in the form of a renewed attempt to block the party's participation in meetings of the North-South Ministerial Council.
The British government yesterday offered no comment on the assertion by the Taoiseach, Mr Ahern, that there was no intelligence linking the IRA to the Castlereagh break-in, despite confirmation by the Acting Chief Constable of the Police Service of Northern Ireland that possible Provisional involvement represented a major line of inquiry.
Meanwhile, there were angry protests from Tory peers yesterday when it emerged that Sinn Féin's four MPs could be given additional access to facilities at the House of Lords end of the Palace of Westminster. A proposed rule change, which would allow the MPs who do not take their seats access to the Lords' library and to observe proceedings from the members' gallery, will be discussed next Tuesday by the Lords administration and works sub-committee.