Scotland's Justice Secretary Kenny MacAskill has said he will take a decision on al-Megrahi's compassionate release 'within the next couple of weeks'.

Al-Megrahi, a former Libyan agent, was sentenced under Scottish law by a special court, sitting in Camp Zeist, in the Netherlands, to life for the bombing of the Pan Am flight 103 over the town of Lockerbie, in which 259 people on board and 11 on the ground were killed.

Moves to free al-Megrahi, the only man to be convicted of the bombing, have been opposed by the US government, and by relatives of the 189 US victims of the atrocity.

US Secretary of State Hillary Rodham Clinton and the US attorney general have informed the Scottish government of their view that al-Megrahi should serve out his term in Greenock jail, near Glasgow.

It emerged Tuesday that seven US senators, including Edward Kennedy and John Kerry, have written a letter to MacAskill urging him to keep al-Megrahi behind bars.

The senators' letter describes the Lockerbie bombing 'a horrific act of international terrorism', adding that 'until the tragic events of Sep 11, 2001, no terrorist act had killed more American civilians'.

While most of the British relatives of the Lockerbie victims have welcomed moves to free al-Megrahi, there has been an overwhelmingly negative response from US relatives.