Megrahi is serving life for the bombing which killed 270 people
Lawyers for the man convicted of the Lockerbie bombing want to see criminal records for 1,160 witnesses who gave statements ahead of his trial.
Margaret Scott QC made the request at a preliminary hearing for the second appeal of Abdelbaset Ali al-Megrahi.
She did not tell the Court of Appeal why his defence wanted the details.
Ronald Clancy QC said the witnesses came from all over the world but added the Crown would try to provide details of all their previous convictions.
Megrahi is in the midst of his second appeal against his 2001 conviction for the atrocity in which 270 people were killed.
He was denied bail earlier this month after applying for interim liberation following his diagnosis with prostate cancer.
Ms Scott asked the court to order disclosure of all the previous convictions of witnesses, from the UK and abroad.
She also asked the Crown to hand over a number of files, notes and material not yet seen by the defence.
She said it was "extremely difficult" to estimate how long the appeal would take, but asked that it be heard in two parts, lasting four and eight weeks, in April and July.
"This appeal must be expedited as quickly as possible in the circumstances of this appellant," she added.
Mr Clancy, for the Crown, said the 1,160 witnesses were spread all over the world, and many had given more than one statement.
He said the Crown was willing to provide the UK criminal convictions, but said they would need help from Interpol for information on crimes committed abroad.
"There are 1,160 witnesses listed, a very large number of them will have provided statements on wholly non-contentious issues, for example the collection of debris across the country," said Mr Clancy.
"The Crown will seek to provide the previous convictions of all these witnesses."
Mr Clancy said it would be even more difficult to provide details of charges which had not yet reached court, arguing there were no procedures available to gather such information.
"The Crown will see what it can do but I can't offer any assurance that anything can be achieved on that score," he said.
A further preliminary hearing is due to take place on Friday to discuss whether secret documents should be handed over to the defence.
Foreign Secretary David Miliband has said the documents could compromise national security.