SCOTLAND'S chief law officer has said there is a "realistic possibility" of a second trial over the murder of 270 people in the Lockerbie bombing.

Last year it emerged that two Libyans had been identified as official suspects by Scottish and US prosecutors over the 1988 Lockerbie bombing in their investigation.

The Crown Office in Edinburgh confirmed at the time that Scotland’s chief prosecutor, lord advocate Frank Mulholland, had issued a formal international letter of request to the Libyan attorney general asking for permission to interview both men.

The Herald: Lord Advocate Frank Mulholland reaffirmed the guilt of Abdelbaset al-Megrahi over the Lockerbie bombing

Now Mr Mulholland has said in discussing the prospect of fresh prosecutions over Britain's biggest mass murder: "I said it takes time, and it will take time, and that's certainly something which we are used to in relation to the Lockerbie inquiry.

"If we get to the stage of seeking the extradition of two named individuals or indeed more persons, I think there's a realistic possibility that there could be a further trial."

READ MORE: Lockerbie suspect was almost tried, says former FBI agent

The Crown Office have not named the two new suspects, but they are believed to be Abdullah al-Senussi, Gaddafi’s brother-in-law and former head of intelligence, who was in a Libyan jail sentenced to death.

The other was said to be Abu Agila Mas'ud who is also in a Libyan jail serving a ten year sentence. He had been identified as the suspected bomb-maker.

Further suspects have included Nasser Ali Ashour, an intelligence officer who supplied the IRA with explosives and weapons in the 1980s and Ken Dorstein, an American documentary film-maker whose brother was killed in the bombing.

Mas’ud was named in the original indictment in 1999 against Abdelbaset al-Megrahi, the only person convicted of the attack, who died in May 2012 after being released by the Scottish government on compassionate grounds in 2009.

The Herald: Lord Advocate Frank Mulholland reaffirmed the guilt of Abdelbaset al-Megrahi over the Lockerbie bombing (Crown Office/PA)

Abdelbaset al-Megrahi

"We're currently at a stage where there are a number of outstanding international letters of request, one of which is seeking the permission of the Libyan authorities to interview two named individuals as suspects," Mr Mulholland told STV.

READ MORE: Lockerbie Revealed: The secret report that damns Scottish justice

"Following all the work that's been going on, and it's been painstaking, it's taken some time, it does take time.

"I hope that the Libyans will grant permission for that to be done. I obviously can't say too much publicly but a lot of work is going on behind the scenes to make that happen.

"What I hope is that this will bear fruit and we can take it to the next stage of seeking the extradition of the two named individuals."

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

READ MORE: Campaigners repeat calls for independent prosecutor to review allegations of Crown wrongdoing over Lockerbie

"I don't fear that," he said. "I think that's a good thing. Without seeking to comment on what the outcome would be, I think the evidence would stand up to a further test.

"We wouldn't be doing this unless we thought that the evidence was sufficiently credible and reliable to have them interviewed as suspects, I think that's the best way to put it."

Campaigners for some Lockerbie victims insist that Libya has been wrongly accused of the bombing.  Megrahi died proclaiming he was innocent.