Lawyers for the man jailed for the Lockerbie bombing have asked the Crown to hand over documents which they said could help overturn his conviction.
Megrahi is making a second appeal against his conviction
A court was told their non-disclosure could indicate that Abdelbaset Ali Mohmed al-Megrahi, 55, was the victim of a "miscarriage of justice".
The Libyan's legal team said they needed the papers to prepare an appeal.
They were granted an extension until 21 December - the 19th anniversary of the disaster in which 270 people in 1988.
The hour-long hearing - which Megrahi did not attend - was the first time the case has come to court since he was granted the right to a second appeal earlier this year.
The full appeal - before a panel of five judges - is likely to be heard next year.
Speaking at the Court of Criminal Appeal in Edinburgh Jim Swire, whose daughter Flora was among the 270 who died when Pan Am Flight 103 exploded over Lockerbie, described it as "a very ominous date".
"We are getting near the 19th anniversary of the murder of our loved ones," he said.
Mr Swire said he was pleased that Scotland's top judge, Lord Justice General Lord Hamilton, seemed to want to speed things up as much as possible.
However, he added that it would be wrong to put too much pressure on the defence.
Alongside the appeal for documents, Defence QC Margaret Scott said a new witness could discredit Maltese shop keeper Tony Gauci whose evidence was crucial in convicting Megrahi at a special court in the Netherlands in 2001.
Ms Scott also said defence forensic experts were working on reports to counter other evidence led at the trial.
The hour-long hearing followed recent speculation that US security services were blocking the handover of potentially crucial information about the timer which detonated the bomb on Pan Am flight 103.
However, Lord Hamilton, sitting with lords Kingarth and Eassie, heard that the Americans were not involved.
"The documents don't come from that government or any of its agencies," said advocate depute Ronald Clancy QC, for the Crown.
He told the court: "The documents in question were passed to the UK Government on the basis that they were regarded as being confidential by the authorities that passed them over.
"That being so, the Crown has always taken the position that, if possible, confidentiality should always be respected."
The Pan Am bombing is regarded as the worst crime in Scottish legal history
Mr Clancy added: "The Crown has been actively pursuing the matter but today it remains unresolved."
Requests had been made to allow the Crown to hand over the documents and it was possible this might happen without the appeal judges having to rule on the issue, the court heard.
Mr Swire said that if the secret documents did not come from the US then it was "pure speculation" which government they belonged to.
In 2002, five judges heard an appeal against Megrahi's conviction but decided that the guilty verdict should stand.
The Scottish Criminal Cases Review Commission, which investigates possible miscarriages of justice, took up the case and after a lengthy investigation concluded in June that Megrahi should have a second appeal.
It was during the SCCRC probe that the issue of documents unseen by the defence emerged.