The son of Lockerbie bomber Abdelbaset al-Megrahi has lost an appeal against his late father’s conviction.

The bombing of Pan Am flight 103, travelling from London to New York on December 21 1988, killed 270 people in Britain’s largest terrorist atrocity.

Former Libyan intelligence officer Megrahi was found guilty in 2001 of mass murder and jailed for life with a minimum term of 27 years – the only person convicted of the attack.

A third appeal against his conviction was heard in November at the High Court in Edinburgh, before a panel of five judges sitting as the Court of Appeal.

Judges have now rejected both grounds of appeal, meaning his conviction stands.

The family of Megrahi said they are “heartbroken” at the decision, and plan to appeal against it at the UK Supreme Court.

Megrahi was released from prison in 2009 on compassionate grounds while terminally ill with cancer, and died in Libya in 2012.

The latest appeal was lodged after the Scottish Criminal Cases Review Commission (SCCRC) referred the case to the High Court in March 2020, ruling a possible miscarriage of justice may have occurred.

Judges then granted his son, Ali al-Megrahi, permission to proceed with the appeal in relation to the argument “no reasonable jury” could have returned the verdict the court did, and on the grounds of non-disclosure of documents by the Crown.

The written judgment rejecting the appeal, delivered by Scotland’s most senior judge Lord Carloway, the Lord Justice General, on Friday, states “the contention that the trial court reached a verdict that no reasonable court could have reached is rejected”.

It adds: “On the evidence at trial, a reasonable jury, properly directed, would have been entitled to return a guilty verdict.

“The contention that the Crown failed to disclose material which would have created a real prospect of a different verdict is rejected.

“Both grounds of appeal having been rejected, the appeal against conviction is refused.”

In a statement released through their lawyer Aamer Anwar after the ruling was published on Friday, the family said: “Ali Al-Megrahi, the son of the only man convicted of the Lockerbie bombing, said his family were left heartbroken by the decision of the Scottish courts, he maintained his father’s innocence and is determined to fulfil the promise he made to clear his name and that of Libya.

“All the Megrahi family want for Scotland is peace and justice, but as Ali stated today their journey is not over, Libya has suffered enough, as has the family for the crime of Lockerbie, they remain determined to fight for justice.”

Megrahi’s original trial was held at a special Scottish court sitting at Camp Zeist in the Netherlands.

During the appeal hearing in November, advocate depute Ronald Clancy QC, for the Crown, said trial court judges were fully entitled to infer Megrahi was involved in the Lockerbie bombing.

He said Megrahi’s use of a false passport to travel to Malta – from where the plane carrying the bomb left just before the atrocity – taken along with other evidence, combined to form a pattern that suggested his involvement.

Claire Mitchell QC, representing the Megrahi family, said evidence in relation to identification was of “poor quality” and the dock identification, when shopkeeper Tony Gauci said Megrahi resembled the man who bought the clothing later found in a suitcase containing the bomb, was “virtually of no value”.

Mr Clancy said that ignores the “important point” that the dock identification was “simply the last of a series of consistent resemblance identifications going back to February 1991”.

Megrahi’s first appeal against his conviction was refused by the High Court in 2002 and was referred back five years later after an SCCRC review.

He abandoned this second appeal in 2009, shortly before his release from prison on compassionate grounds.

Meanwhile, the US Justice Department charged a “third conspirator” in connection with the bombing on the 32nd anniversary of the atrocity last month.

The US alleges Abu Agila Mohammad Masud Kheir Al-Marimi was the bombmaker and has charged him with terrorism-related crimes.

A second suspect, Al Amin Khalifa Fhimah, stood trial with Megrahi but was acquitted.

The judgment delivered by Lord Carloway states: “This appeal is then concerned essentially only with two issues: (1) whether the verdict was unreasonable having regard to the quality of Mr Gauci’s testimony; and (2) whether the disclosure of certain material would have created a real possibility of a different (ie an acquittal) verdict.

“In this context, the appeal is not directly concerned with an examination of evidence which might point to other persons or organisations being involved in the murder, except in so far as that involvement might exclude Mr Megrahi as a participant in the ingestion of the bomb on to an Air Malta flight to Frankfurt, from where it was transferred to the flight departing from London Heathrow.”

Scotland’s Lord Advocate James Wolffe QC said the investigation into the atrocity continues and there remain suspects under active investigation.

He said: “The bombing of Pan Am 103 is, to this day, the deadliest terrorist attack on UK soil and the largest homicide case Scotland’s prosecutors have ever encountered in terms of scale and of complexity.

“The evidence gathered by Scottish, US and international law enforcement agencies has again been tested in the Appeal Court, and the conviction of Abdelbaset Ali Mohmed Al Megrahi stands.”