The Lockerbie bombing was orchestrated by Iran and carried out by a Syrian-based terror group, according to a former Iranian intelligence officer.
The sensational new revelations claim Britain’s worst terrorist atrocity was ordered in retaliation for a US strike on an Iranian passenger plane and not on the orders of Libyan dictator Muammar Gaddafi.
Libyan Abdelbaset al-Megrahi is the only person to be convicted of the bombing of Pan Am flight 103 over Scotland in which 270 people were killed more than 25 years ago.
Megrahi, who was released from jail by the Scottish government on compassionate grounds after being diagnosed with prostate cancer, died in 2012 still protesting his innocence. His family plan to appeal against his conviction.
But former Iranian intelligence officer Abolghassem Mesbahi – now living under a witness protection scheme in Germany – has told an Al Jazeera documentary that the bombing was ordered by Tehran and carried out by the Syrian-based Popular Front for the Liberation of Palestine-General Command (PFLP-GC).
Former Iranian leader Ayatollah Khomeini ordered the attack, he claimed, in retaliation for a US navy strike on an Iranian commercial jet six months earlier, in which 290 people died. The US ship apparently mistook the plane for an F-14 fighter jet.
Speaking to Al Jazeera, Mr Mesbahi said: "Iran decided to retaliate as soon as possible. The decision was made by the whole system in Iran and confirmed by Ayatollah Khomeini.
"The target of the Iranian decision makers was to copy exactly what's happened to the Iranian Airbus. Everything exactly same, minimum 290 people dead. This was the target of the Iranian decision makers."
The report also says that the bomb was planted on Pan Am flight 103 at Heathrow Airport, not at Malta as suggested during the trial of al-Megrahi.
US Defence Intelligence Agency cables at the time reported that the leader of the PFLP-GC had been paid to plan the bombing, the broadcaster said.
The Crown Office has previously said the alleged involvement of the PFLP-GC was addressed at the original Lockerbie trial.
A successful application from Megrahi's family to the Scottish Criminal Cases Review Commission (SCCRC) could start the third appeal into the conviction.
Megrahi lost his first appeal in 2002, one year after he was found guilty of mass murder and jailed for life.
The SCCRC recommended in 2007 that Megrahi should be granted a second appeal against his conviction. He dropped his appeal two days before being released from prison in August 2009 on compassionate grounds.
In December, the Libyan attorney general announced he had appointed two prosecutors to work on the case. For the first time they met Scottish and US investigators who are trying to establish whether there are other individuals in Libya who could be brought to trial for involvement in the attack.
Since the fall of the Gaddafi regime, British and US investigators have been working to establish if there are other individuals in Libya who could be brought to trial for their involvement in the attack.
A group of UK-based families also hope to overturn the conviction of Megrahi, united in their belief that he did not act alone.
Dr Jim Swire, whose daughter Flora, 23, was among the dead, is among those applying to the Scottish Criminal Cases Review Commission for a fresh appeal against Megrahi’s conviction.
He has said that if Megrahi’s appeal is overturned, it may “blast a route to a proper inquiry through very reluctant authorities”.