The Saville Tribunal has postponed a crucial ruling on secret British
Security Service evidence alleging Sinn Fein vice-president Mr Martin McGuinness fired the first shot on Bloody Sunday.
The allegation was made by an agent codenamed "Infliction" who has since been granted a Public Interest Immunity (PII) certificate meaning his testimony cannot be examined by the tribunal unless an application to the courts is made.
The certificates were submitted by the British Home Office and its Ministry of Defence.
The Inquiry chairman, Lord Saville, said the ruling on PII applications was likely to be put off "for a week or two at least" as a result of doubts raised about the source by ex-MI5 officer David Shayler in Sunday's Observer.
Mr Shayler claimed in his article that the agent who made the allegations about Mr McGuinness - codenamed "Infliction" - was a known liar who was eventually "terminated" as an intelligence informant.
PA