Lawyers for the former Libyan agent jailed over the 1988 Lockerbie plane bombing launched an appeal on Tuesday against his conviction over the attack, which killed 270 people.

Abdelbaset Ali Mohmet al-Megrahi is serving a life sentence with a minimum term of 27 years over the downing of Pan Am flight 103 in the skies above the Scottish village of Lockerbie, while en route from London to New York.

The Libyan — who has repeatedly protested his innocence — failed last year to secure his release pending the appeal, on the grounds that he was dying from cancer.

The new legal hearing began in Edinburgh nearly two years after the Scottish Criminal Cases Review Commission (SCCRC) referred the case for appeal, saying there were grounds to suspect that a miscarriage of justice may have occurred.

Megrahi was sentenced in 2001 by three Scottish judges sitting at an extraordinary tribunal in The Netherlands for blowing up the airliner on the night of 21 December 1988.

The blast killed all 259 on board and another 11 people on the ground were killed by falling debris, and plunged ties between oil-rich Libya and the West into a deep chill that has only thawed in recent years.

A Libyan official said earlier this month that Tripoli plans to seek the extradition of Megrahi, to allow him to continue his sentence in a Libyan prison.

In May 2007, Britain and Libya signed a protocol agreement on the transfer of prisoners which the Libyan source says has been ratified by the two countries. The documents were due to be exchanged this month.

The 57-year-old Libyan former intelligence officer has been diagnosed with advanced prostate cancer, but a Scottish court last November refused to free him on bail.

The court cited experts as saying Megrahi could live for years depending on how successful his treatment is, but his wife Aisha told AFP in February that he "is in danger of dying" because of his worsening cancer.

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