The timer fragment is the size of a thumbnail
The Crown Office has dismissed an MSP's claims that she uncovered new evidence which could have compromised the Lockerbie prosecution as "misleading".
The SNP's Christine Grahame said a fragment of bomb timer used in the atrocity left Scotland twice before the trial of Abdelbasset al-Megrahi.
She said a Freedom of Information inquiry response revealed the evidence had been taken to Germany and the US.
The Crown Office said Megrahi's defence team knew of the moves.
A total of 270 people died when Pan Am flight 103 exploded over the town of Lockerbie in southern Scotland.
A timer fragment about the size of a thumb nail, known as PT-35, was taken to the Siemens company in Munich in April 1990 by Scottish police officers.
The fragment was also taken to the United States.
PT-35 was crucial to the case as it was found in fragments of clothing bought in Malta.
It was these, the prosecution claimed, that linked Megrahi to the bombing.
The Libyan was convicted of the bombing in 2001, after a trial at a specially-convened court in the Netherlands.
Megrahi was convicted of the Lockerbie bombing in 2001
Ms Grahame, who is convinced Megrahi is innocent and has been a persistent campaigner for a full inquiry into the causes of the Lockerbie disaster, said that the chief prosecutor at the time did not know the evidence had been taken out of Scottish jurisdiction and control.
She said this left "a very serious question mark" over the central piece of evidence used to convict Mr Megrahi.
A Crown Office statement said there was "absolutely nothing new" about Ms Grahame's claims.
It said: "Contrary to what is being claimed by Ms Grahame, the fact that the fragment of MST-13 timer known as PT-35 was taken to West Germany in 1990 by Scottish police officers was known to Mr Megrahi's defence team prior to his trial and indeed was presented to the court by the Crown as evidence in the trial.
"During the trial Hans Brosamle of Siemens was called as a Crown witness and described examining PT-35 in Munich to the court."
It added: "At no time during the investigation was the timer fragment ever outside the custody and control of the Scottish police officers, or forensic scientists at the Royal Armament Research and Development Establishment."
Megrahi served eight years in prison before being released in August on compassionate grounds, due to his terminal illness.
His release came days after he had dropped a second appeal against his conviction.
Megrahi has always protested his innocence and has published documents on the internet which would have been used in his appeal.