The Lockerbie bombing was ordered by Iranian officials in retaliation for the US shooting down one of its civilian aircraft, a high level defector claims.
Former Iranian intelligence official Abolghassem Mesbahi, who has defected to Germany, said that the attack was organised in Tehran and carried out by the Syrian-based Popular Front for the Liberation of Palestine-General Command (PFLP-GC).
The claim follows a Channel 4 News report in December 2013, in which it was revealed that an undercover CIA agent said he was told by up to 15 high-level Syrian officials that the PFLP-GC was involved in the December 1988 bombing, which killed 270 people.
Dr Richard Fuisz said in a US court deposition that he was told numerous times between 1990 and 1995 who was behind the attack. He said that interaction with PFLP-GC leader, Ahmed Jibril, was “on a constant basis” and that he planned the bombing.
His deposition came too late to be used in the trial of Libyan Abdelbaset al-Megrahi, who was convicted and jailed in Scotland.
But the claims therein have now backed up by Mr Mesbahi, who said in an Al-Jazeera documentary that Iran decided to retaliate “as soon as possible” after a US Navy ship shot down the Iranian commercial jet in July 1988, killing 290 people. The ship apparently mistook the plane for an F-14 fighter jet.
“The decision [to retaliate] 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.”
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 and died in 2012.
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.
A Crown Office spokesman said: “Mesbahi’s claim that Iran was responsible was first reported in the media in the late 1990s and was available to the defence before the trial but they did not call him as a witness.
“The wider alleged involvement of the PFLP-GC has been repeatedly reported over many years but was addressed in full and rejected at the original trial.
“The only appropriate forum for the determination of guilt or innocence is the criminal court, and Mr Megrahi was convicted unanimously by three senior judges. His conviction was upheld unanimously by five judges, in an Appeal Court presided over by the Lord Justice General, Scotland’s most senior judge.
“As the investigation remains live, it would not be appropriate to offer further comment.”