THE controversy over the Lockerbie bombing and the conviction of former Libyan spy Abdelbaset Ali Mohmed al Megrahi is set to be raised significantly later this year when relatives hold a 25th anniversary memorial service at Westminster Abbey.

Jim Swire, who lost his 23-year-old daughter Flora in Britain's worst terrorist atrocity, is one of the relatives behind the move, which could see several hundred people paying their respects to the 270 victims of the tragedy at the service on December 21 in London.

The 76-year-old GP, who has been at the forefront of the relatives' campaign for justice, signalled that after 25 years he would be handing the leading role in the relatives' campaign for justice to someone else.

He did not elaborate, but said: "If the authorities can't get their heads around the fact that we require the truth after 25 years, then they have had long enough. I intend to take more of a backseat role."

Dr Swire said there would be other significant supporters of the families' campaign for justice, who would take the lead and "expose the fact that the evidence against Megrahi was nonsense".

He pointed to two pieces in particular which made the case against the late Libyan spy invalid – a fake circuit board used at the trial and information about a break-in at Heathrow the day before the terrorist atrocity.

Allegations, which include claims that prosecutors passed false information to the court and key statements were deliberately buried, are now being investigated by Patrick Shearer, the former Dumfries and Galloway Chief Constable.

Dr Swire accused the Crown Office of being "too laidback, lethargic and over-confident in their own infallibility", saying the implications of someone planting fake evidence were "terrible; I feel most angry about it".

He explained: "After 25 years, we wanted to have another memorial event. It's not about the Crown Office or Scottish justice, although they will have to justify things sooner or later. This is not just an issue for the relatives, but for the people of Scotland."

A spokesman for the Crown Office said: "We have no comment to make on Dr Swire's personal views. The evidence gathered by the police and prosecutors was rigorously tested at the trial and two appeals against conviction. At the end of this lengthy process the conviction still stands.

"The investigation into the others who acted with Megrahi in the bombing of Pan Am 103 remains live.

"Given recent events in Libya and the change in regime, there is the possibility of future criminal proceedings."