Lawyers for the man convicted of the Lockerbie bombing want to know the criminal records of more than 1000 witnesses who gave statements ahead of his trial.

Lawyers for the man convicted of the Lockerbie bombing want to know the criminal records of more than 1000 witnesses who gave statements ahead of his trial.

At a preliminary hearing at the Court of Appeal yesterday, Margaret Scott, QC, asked for the previous convictions of all 1160 witnesses to be revealed.

Ms Scott did not say why the defence team wanted the information ahead of Abdelbaset Ali Mohmed Al Megrahi's second appeal. But she said the appeal hearing would take at least 12 weeks, and could start in April.

Megrahi has been given leave to appeal for a second time against his conviction for killing 270 people by bombing Pan Am flight 103 over Lockerbie in December 1988.

The Libyan is currently serving his minimum 27-year life sentence at Greenock Prison. Earlier this month, three judges ruled the 56-year-old must stay in jail ahead of the appeal hearing, despite being terminally ill with prostate cancer.

Lawyers had argued he should be released on "compassionate" grounds, but the judges said he was not yet ill enough to justify this.

Megrahi has already lost one appeal against his 2001 conviction for Scotland's worst mass murder. Last year the Scottish Criminal Cases Review Commission, which investigates possible miscarriages of justice, sent the case back to the Court of Criminal Appeal.

Megrahi's lawyers say fresh evidence in the form of expert reports will clear his name.

The former secret service agent was not present for yesterday's hearing before Scotland's top judge, Lord Hamilton, sitting with Lords Kingarth and Eassie.

Ms Scott asked the court to order disclosure of all the previous convictions of the witnesses, from the UK and abroad, and 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.

Advocate depute Ronald Clancy QC, for the Crown, said the 1160 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 1160 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.

A further preliminary hearing is due to take place today to discuss whether secret documents should be handed over to the defence.

Foreign Secretary David Miliband says the documents, from an unidentified foreign government, would breach confidence, damage international relations and compromise the war on terror.