Pressure is growing for a full public inquiry into the Lockerbie disaster, in response to new evidence that suggests a miscarriage of justice took place in the trial of the Libyan convicted of the bombing.

A judicial review of Abdul Baset Ali al-Megrahi’s conviction is to decide this week whether to refer his case back to the Appeal Court. If it does, al-Megrahi would almost certainly be cleared.

“Where that would leave the Scottish judicial system and the Scottish police, God knows,” said Tam Dalyell, the former MP who has long campaigned for an inquiry. Jim Swire, whose daughter, Flora, died in the 1988 bombing, described al-Megrahi’s conviction as “one of the most disgraceful miscarriages of justice in history”.

The Libyan is serving a life sentence in a Scottish jail for his part in placing a bomb aboard Pan Am Flight 103, which exploded over the town of Lockerbie, killing 270 people.

The repercussions of a referral for Britain and the US would be far-reaching. The trial of al-Megrahi and his co-accused, Amin Khalifa Fhimah, was the most expensive criminal prosecution carried out by Britain. It was held in a specially constituted court in The Netherlands and is estimated to have cost about £80 million.

The case was brought in 2001 and there have long been doubts about the safety of the conviction. The original evidence suggested the involvement of Syria and Iran and an organisation known as the Palestianian Front for the Liberation of Palestine-General Command. An associate of the group, Abu Talb, who is serving a life sentence for terrorist offences in Sweden, was named by investigators as a suspect, and evidence emerged that he and the group received $11 million (£5.5 million) from Iranian sources after the bombing.

Attention switched to Libya after the Gulf War, when Iran became an important ally. A crucial piece of evidence – a fingernail-sized piece of a circuit board believed to have been part of the bomb concealed inside a Toshiba cassette recorder – was picked up in the search area around Lockerbie. Investigators claimed that it had been wrapped in clothing packed inside a briefcase, which was traced back to a shop in Malta. The shopowner identified al-Megrahi and a colleague as the buyers.

The prosecution case was that the two Libyans smuggled the bomb aboard a flight from Malta to Frankfurt, where it was switched to a connecting flight, via Heathrow, to New York. In the course of the trial, weaknesses in the prosecution case emerged.

Now new evidence has been produced to challenge further the safety of the conviction:

— The Maltese shopkeeper, whose identification of al-Meg-rahi was crucial, changed his story several times in the course of inquiries, first identifying Abu Talb as the man who had entered his shop, then contradicting his evidence about individual items he had sold.

— A log that detailing the exact dates of the discovery of evidence was altered. Page numbers were changed and a new page containing additional evidence was inserted at a late stage. The description of the clothing recovered – whether damaged or not – was also changed.

— One of the investigators claims that evidence was fabricated, and that some of his colleagues were unhappy when the focus of police inquiries switched from Syria and Iran to Libya.

— Claims by a Heathrow luggage-handler that he had noticed the briefcase had been added at the last minute to the Pan Am flight were never properly tested.

— Al-Megrahi, who was said to have been a Libyan intelligence officer working at a Maltese airport, was in fact part of a sanctions-busting team, and had nothing to do with airport work. He claims that he never met the Maltese shopowner.

The Scottish Executive refused to comment on the new reports. “It is not for Scottish ministers to comment or preempt the outcome of this review,” it said. “It is the strong view of the Scottish Government that due process of law will be followed and seen to be followed in all matters pertaining to this case.”

Mr Dalyell said: “I have no doubt that evidence was planted, and I have said so repeatedly in the Commons. Only a full, public and nonadversarial inquiry can finally settle this matter.”

Road to review

December 21, 1988 Pan Am flight 103 crashes over Lockerbie, killing 270

1989 Investigation points to Palestinian group after arrest of terrorist suspects in Germany

1990 Investigation shifts to Libya as fragment of radio is linked to Pan Am bomb

1992 UN sanctions imposed on Libya for failing to cooperate

December 16, 1998 Libya agrees to hand over suspects if trial is held in The Netherlands

December 7, 1999 Two suspects, al-Megrahi and Fhimah, appear in court at Camp Zeist

January 31, 2001 Al-Megrahi found guilty of murder; Fhimah acquitted

2002 Al-Megrahi’s appeal turned down

November 24, 2003 Al-Megrahi sentenced to life. Lawyers submit case to review commission

June 28, 2007 Date on which judicial review will announce decision on whether to refer case to Court of Appeal

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