LIBYA has appointed two prosecutors to work on the Lockerbie case, less than a year after the government in Tripoli declared the investigation closed.
Lord Advocate Frank Mr Mulholland revealed the move last night, just days before the 25th anniversary of the tragedy which killed 270 people.
He said it marked "a significant step" and the Libyan officials will now work alongside investigators from Scotland and America.
In February, the new Libyan government made clear that in its view the Lockerbie case was closed and that it did not want to rake over the past but look to the future.
"The matter was settled with the Gaddafi regime. I am trying to work on the current situation rather than dig into the past," declared Salah al Marghani, Libya's Justice Minister.
His deputy, Hameda al-Magery, added: "Britain and America are asking us to reopen this file but this is something of the past. This is over. We want to move forward to build a new future and not to look back at Gaddafi's black history. This case was closed and both UK and US Governments agreed to this. They had their compensation."
This apparently firm rejection came just weeks before detectives from Police Scotland travelled to Libya to begin their inquiries into Britain's worst terrorist atrocity in a bid to uncover new evidence. At the time, David Cameron said he was "delighted" that Scottish detectives were going to the Libyan capital.
The u-turn was welcomed by Mr Mulholland, who said: "As a result of developing good relations and understanding of what we're trying to achieve, Libya has appointed two prosecutors to work with the US and Scottish prosecutors. So that's a welcome development and hopefully this will progress matters.
"I have met and spoken to Libyan senior officials on a number of occasions and my judgement, my assessment is, it is a sincere move."
Police Scotland Deputy Chief Constable Iain Livingstone said: "It is complex. It is not a stable operating environment in Libya at the moment but we are in constant contact with the Crown and the Foreign Office to see if there is an opportunity. Police Scotland will go there and seek to find evidence and report that to the Crown."
It is thought Libya's official involvement could open avenues that otherwise might have been closed to Scottish investigators.
While an argument continues over whether the late Libyan agent Abdelbaset Mohmed Ali al Megrahi, the only person to be convicted of the bombing, was involved, most observers believe that Britain's worst terrorist atrocity act masterminded by a state government.
One person detectives will be hoping to interview is Abdullah al Senussi, former head of Libya's intelligence agency. He is incarcerated in Tripoli, accused of ordering massacres during the revolution two years ago.
On December 21 1988, 270 people died when Pan Am Flight 107 exploded over Lockerbie. On Saturday, relatives of victims will hold memorial services in Lockerbie, Westminster Abbey and at Arlington National Cemetery in the US.