ABDELBASET Ali Mohmed al Megrahi could "easily" live another year with proper medication, according to the UK's leading prostate expert, raising fresh doubts about the decision to return him to Libya on compassionate grounds.

Professor Roger Kirby, chairman of the charity Prostate UK and director of The Prostate Centre, said justice secretary Kenny MacAskill could have "egg on his face" after accepting that Megrahi's terminal prostate cancer left him just three months to live - the benchmark for compassionate release.

In an article in today's Sunday Herald, Prof Kirby says he is "extremely sceptical" about the three months prognosis.

Megrahi revealed to The Herald and Sunday Herald writer Lucy Adams in Tripoli last week that he was due to re-start chemotherapy, which another expert said could prolong his life.

The experts' comments put further pressure on MacAskill to explain his decision ahead of a parliamentary debate this week on the release of the only man ever convicted over the bombing of Pan Am Flight 103 over Lockerbie in 1988 in which 270 people died.

Megrahi, who was found guilty in 2001, was freed by the justice secretary earlier this month after a report concluded that the Libyan had around three months to live.

However, it has since emerged that only one of the doctors involved in the case believed that the three-month timescale was a "reasonable" estimate.

It can also be revealed that Andrew Fraser, the Scottish Prison Service doctor whose report recommended release, is a specialist in drug addiction rather than cancer.

David Neal, professor of surgical oncology at Addenbrooke's Hospital, Cambridge, said: "If he has metastatic prostate cancer, there is evidence that chemotherapy can improve survival by around a month or six weeks."

A spokesperson for the Scottish government said: "It was the conclusion of the report submitted by the Scottish Prison Service Director of Health and Care that The clinical assessment is that a three-month prognosis is now a reasonable estimate for this patient.' This view is based upon an analysis of all of the views expressed and the consensus of the medical experts."