Libya's transitional justice minister Mohammed al-Alagi said on Monday that Abdelbaset al-Megrahi, the only person convicted in the 1988 Lockerbie bombing, should not face a new prosecution.
His comments came after officials said prosecutors in Scotland had formally asked Libya's new government to help them with the investigation into the bombing.
"Personally I did not receive any request (from prosecutors), but what I know, as a lawyer, and as a justice minister, is that Abdelbaset al-Megrahi was prosecuted and convicted and he spent more than 10 years in prison," Alagi told AFP.
"Then they decided to release him on compassionate grounds and this was approved by the Scottish and British governments. And I say we should not prosecute the same person twice."
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Scottish authorities in particular want Libya's National Transitional Council (NTC) to make evidence and witnesses available for their probe into the attack on Pan Am flight 103 in which 270 people died.
Megrahi, the only person convicted of the bombing, was released on compassionate grounds on August 20, 2009 after doctors said he had only three months to live. He is still alive.
The Pan Am jumbo jet exploded over the Scottish town of Lockerbie on December 21, 1988, killing 259 people on the aircraft, mainly Americans, and 11 on the ground.
A second Libyan man, Al Amin Khalifa Fhimah, also stood trial at a Scottish court sitting in The Netherlands with Megrahi, but was acquitted in the trial in 2001.
Secret files released earlier this month showed that Moamer Kadhafi's now-toppled regime warned of "dire consequences" for relations between Libya and Britain if Megrahi died in jail in Scotland.