Almost 20 years since Pan Am Flight 103 was brought down in Britain's worst terrorist outrage, the Lockerbie case came back to court yesterday. Rarely out of the headlines since the day of the attack in December 1988, it has tested the Scottish legal system to its limits. In the High Court, the case took a new turn when lawyers for the Libyan man convicted of the bombing sought bail for their client.

Margaret Scott, QC, for the defence, set out three reasons for requesting the release of Abdul Baset Ali al-Megrahi: the strength of his appeal, delays in the appeal process, and his deteriorating health. It was disclosed last month that al-Megrahi has advanced cancer.

Ronnie Clancy, QC, for the Crown, asked the appeal judges to deny the request because of the “incomparable gravity” of the offence.

Lord Justice General Lord Hamilton, Lord Kingarth and Lord Wheatley said that they would deliver their decision at a later, undisclosed date.

Al-Megrahi, 56, who has consistently protested his innocence, is serving a life sentence with a minimum term of 27 years after being convicted in 2001 of the atrocity. All 259 men, women and children on board the aircraft died, along with 11 residents of the Scottish Borders town who were killed by falling wreckage.

Initial inquiries suggested the involvement of a Syrian-based terrorist group, but suspicion later switched to Libya. Al-Megrahi was found guilty after a unique trial, held in the Netherlands but under Scottish law.

At the 2-hour hearing yesterday, Ms Scott said that there were “unusual and compelling” reasons to grant bail. These included the “comprehensive nature” of Al-Megrahi's appeal, due to be heard next year, and a series of delays that have set back the appeal process. It has been 17 months since the Scottish Criminal Cases Review Commission referred the case back to court. She said that there was also a case for bail because of his personal circumstances. “The appellant is terminally ill,” she said. “His suffering will be reduced if he is released from prison conditions.”

The court was told that al-Megrahi was married and had five children aged between 25 and 10, and two grandchildren. His family had moved to Glasgow and had visas to visit and reside in Scotland. If released on bail al-Megrahi would stay with them, Ms Scott said. Al-Megrahi was not considered a “flight risk”, she added.

Opposing bail, Mr Clancy said that some of the grounds of appeal were likely to fail, and that al-Megrahi's illness could be satisfactorily treated in prison. He also maintained that the delays in his appeal being heard were not the fault of the Crown.

Mr Clancy requested that if al-Megrahi were granted bail, he should not be allowed to travel for more than 10 miles unless for court appearances or medical treatment. He should also be made to report to a police station every week.

Jim Swire, whose daughter died in the atrocity, was in court for the hearing. He said that he approved of al-Megrahi being granted bail. “He is a human being, he is dying, and he needs to be with his family,” he said.

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