An elaborate bugging device found at the home of one of Gerry Adams's staff has all but capsized preparations for crucial talks set for England later this month.
The party's chief negotiator in the ongoing talks process, Martin McGuinness, today pointed out that British Direct Ruler Paul Murphy would have authorised the bugging operation and demanded a full statement.
The listening equipment was found in the loft area of a home in west Belfast. Workmen discovered the device after being called out by a woman who works at Mr Adams' constituency offices.
Throughout the conflict in the North of Ireland, spying devices have been discovered in homes and vehicles used by Irish Republicans. During the negotiations leading up to the 1998 Good Friday Agreement, spying devices were found in a car frequently used by Sinn Féin leaders.
However, the device found recently was described as much more elaborate than other such devices, consisting of ten separate pieces of equipment which filled the roof-space of the house. It was connected to a small microphone built into the living room ceiling of the house.
Following the tenth anniversary of the IRA ceasefire, republicans said the find provided proof that the British government was not committed to any peace process.
Mr McGuinness said today: ``This is a serious breach of faith by the British government and I believe that it comes directly from within the Northern Ireland Office.
``I have to presume that it was authorised by the Secretary of State Paul Murphy in his role as head of the NIO and rest assured I will be raising this directly with him.
``The `no comment' approach by the NIO will not wash.''
With a critical new bid to salvage the Good Friday Agreement still reeling from a sectarian outburst by a defiant DUP leader Ian Paisley last week, Mr McGuinness warned that the development could have serious repercussions for intensive talks later this month.
``Gerry Adams yesterday raised this very serious turn of events with the British Prime Minister Tony Blair. People should not underestimate the effects of this,'' the Mid Ulster MP said.
``Clearly this NIO spying operation on Sinn Féin raises very serious issues and very serious questions about the continuing negative role being played by the NIO securocrats at the heart of the British system.
``Tony Blair needs to tackle head on those within the NIO who are hostile to the peace process and hostile to republican involvement in it.''
The British government has predictably refused to comment on the find.