A Maltese shopkeeper whose evidence was key to the conviction of Abdelbaset Al-Megrahi over the Lockerbie bombing has died.

Tony Gauci died of natural causes at his home in Malta last Saturday.

Gauci said Megrahi "resembled a lot" a Libyan who had bought clothes which were inside the suitcase that held the bomb.

That identification was a cornerstone of the prosecution case at Megrahi's trial at Camp Zeist in the Netherlands over the nine-month trial which started in May 2000.

The items were wrapped around the bomb which exploded as the Pan Am 103 flight flew over Scotland in December 1988.

Megrahi was convicted of murdering all 259 passengers and crew on board and a further 11 residents of Lockerbie, who died when the wreckage fell on their town on December 21, 1988.

Gauci's evidence was heavily disputed by Megrahi's defence at the trial and doubts have since been raised about his reliability.

Scottish and American police officers have described Gauci as an honest, simple man who bravely co-operated with the inquiry in the fact of constant threats.

Megrahi always protested his innocence and in 2007 questions over Gauci's evidence led to the Libyan winning a second appeal against his conviction.

The Scottish Criminal Cases Review Commission referred the case back to the appeal court, having decided there were six grounds which raised doubts about the safety of the case against him.

They raised concerns about the date when the clothes were said to have been purchased, Gauci's identification of Megrahi, and whether he had received a reward from the Americans for giving evidence against the Libyan.

Megrahi dropped his second appeal in 2009 after he was diagnosed with terminal cancer.

Megrahi, who remains the only person to be convicted of the bombing, was released by the Scottish Government on compassionate grounds in August 2009.

Megrahi returned to Libya where he died in May 2012.

A retired police officer and close family friend of the Gauci family told STV News that he was a "man of great honesty and integrity".

He said: "He was astounded when Megrahi was released, especially as nobody from the UK authorities contacted him to let him know. They found out via the media."

Gauci's friend, who asked not to be named, said his family was "outraged" that there had been no warning or protection plan put in place for him by MI6 after Megrahi was released.

Scotland's former chief law officer Frank Mulholland told STV News earlier this year that he believes there is a "realistic possibility" of a second trial over the bombing.

Scottish and American investigators revealed in 2015 that they had identified two Libyans as suspects over the atrocity but since then very little has been said publicly about the case.

The lord advocate acknowledged any new Lockerbie trial would involve a public re-examination of the disputed evidence from Megrahi's.