THE UK’s worst terrorist atrocity – the Lockerbie bombing – is returning to court as a crowdfunder is launched to pay for lawyers bidding to posthumously clear the only man to be convicted of the crime.

A total of 270 people died in the attack as Pan Am Flight 103 was on its way from London to New York on December 21, 1988.

Abdelbaset al-Megrahi was jailed for a minimum 27 years after being found guilty of mass murder at a trial in the Netherlands. He abandoned his initial appeal in 2009, shortly before being freed from prison on compassionate grounds.

Megrahi died in 2012, but his son Ali al-Megrahi is appealing against the conviction on his behalf.

The appeal was lodged after the Scottish Criminal Cases Review Commission (SCCRC) referred the case to the High Court in March following a ruling there may have been a miscarriage of justice.

Judges allowed the appeal in relation to the argument that “no reasonable jury” could have returned the verdict the court had and on the grounds of non-disclosure of documents by the Crown.

Aamer Anwar, the lawyer representing the family, claimed the Libyan government had “failed to honour its promise of funding the appeal” and has launched a crowdfunder.

He said the legal team had worked “pro-bono” for more than six years and had they charged the costs would run into millions.

The appeal hearing will start at the High Court in Edinburgh on Tuesday and is expected to last until the end of the week.

READ MORE: 'A booming new border': Why Scottish independence would benefit Annandale

Anwar said: “There has been a widespread assumption that our legal team have been paid fees to date, that is simply not true as they have worked pro-bono for what can only be described as the biggest criminal appeal in UK legal history.

“Despite promises over the course of several years, the Libyan government has so far failed to fund the case and so we are now forced to look to the public to support us however much they can.”

The lawyer said: “In conclusion, for the Megrahi family and many of the British families of the victims supporting the appeal, there is finally hope this is the end of a very long journey. For my team it has been six long years but for the families we represent it has been nearly 32 years of struggle for truth and justice.”

Central to the appeal are items said to have been bought by Megrahi in a shop in Malta owned by Tony Gauci, which were found in the case housing the bomb that destroyed Flight 103.

The SCCRC agreed a miscarriage of justice may have arisen as the court could not reasonably find Megrahi had bought them on the evidence before it. Gauci also received a $2 million (£1.5m) reward from the US for giving evidence against Megrahi.

Anwar added: “The judges, following the hearing in August, authorised the founding of the appeal on the additional ground of non-disclosure of the CIA cables. They also ordered that protected documents held by the UK Government should be released to the court.

“Thereafter a private court hearing … considered whether the documents over which Public Interest Immunity is claimed should be released to the appellant. A decision is still pending on whether the protectively marked documents will be released to us.”

The UK and Libyan governments have been approached for comment.