Abu Agila Mas’ud, who will stand trial next May, denied making the device that caused Pan Am Flight 103 to explode over the Scottish Borders 36 years ago.

It is thought that Mr Mas’ud may have known the late Abdelbaset al-Megrahi, the only man convicted over the atrocity. During the preparation for his trial in the Netherlands, however, Mr Megrahi told his lawyers that he did not know Mr Mas’ud.

Mr Megrahi was convicted on 31 January 2001 of the murders of the 243 passengers and the 16 crew on board Pan Am Flight 103 from London to New York, and 11 residents of Lockerbie, on 21 December 1988.

A judge in the US federal court in which the trial is taking place is considering allowing people affected by the case to watch the trial remotely. As a result, the FBI is trying find those who meet the legal definition of victims.

The FBI wants a list of individuals “who meet the statutory definition of victim and wish to have access to the court proceedings”.

A victim is defined as someone who was “present at or near the scene in Lockerbie when the bombing occurred or immediately thereafter” and who suffered “direct or proximate harm (e.g. physical or emotional injury) as a result”.

The second group includes “the spouse, legal guardian, parent, child, brother, sister, next of kin or other relative of someone who was killed on Pan Am 103 or killed or harmed on the ground in Scotland or someone who possesses a relationship of a similar significance to someone who was killed or harmed in the attack”.

The FBI stated: “We understand that this notice may be unexpected and raise questions for many who are connected to this tragedy.

“Please accept our apologies for any apprehensions caused by this sudden outreach, and rest assured that we have a team of dedicated individuals prepared to address any concerns you may have about this process.”