The identity of the mystery witness - a Libyan - is known to The Independent and has been protected since the man went into hiding in the US in 1992 or earlier. His credibility will be crucial to the full trial, which is expected to begin on 2 February next year.
The news comes as attention focuses on Camp Zeist, a former US base in the Netherlands, where Abdel Basset Ali al-Megrahi, 47, and al-Amin Khalifa Fhimah, 43, will appear tomorrow for the first time in front of a Scottish judge.
Lord Sutherland will hear a challenge from the men's lawyers to the conspiracy charge, which, it will be claimed, should not be presented to a Scottish court. They will claim that since the alleged conspiracy took place outside Scotland, the court is acting beyond its jurisdiction.
Lawyers for the prosecution were yesterday declining to comment on their contacts with witnesses. The Libyan witness's statements are believed to implicate both defendants in a plot which led to the placing of the bomb on Pan Am flight 103 from Frankfurt to New York, via London, in December 1988.
The two men, alleged to be Libyan intelligence officers, deny the charges of murder, conspiracy to murder and breaching the 1982 Aviation Security Act. They were extradited from Libya to Scottish custody in April this year after an eight-year battle.Reuse content