Tensions continued between the United States and Britain over the release of convicted Lockerbie bomber Abdel Basset al-Megrahi, with the Scottish justice secretary defending the move on Saturday, dpa reported. Scottish Justice Secretary Kenny MacAskill was reported have received an "outraged" letter from the director of the US Federal Bureau of Investigations, Robert Mueller. A former prosecutor who played a key role in the investigation into the 1988 aeroplane bombing that killed 270 people, Mueller stated: "Your action in releasing Megrahi is as inexplicable as it is detrimental to the cause of justice." Mueller added that freeing the Libyan "makes a mockery of the rule of law" and "gives comfort to terrorists around the world." The Scottish government, which has jurisdiction in the case, said in a statement that its justice secretary reached his conclusions on the basis of Scotland's "due process, clear evidence, and the recommendations from the parole board and prison governor." The statement also said: "Mr MacAskill could not have consulted more widely - he spoke with the US families, the US Attorney General, Secretary of State Clinton and many others." "Compassionate release is not part of the US justice system but it is part of Scotland's," the statement also said, adding that MacAskill would be replying to Mueller's letter "in due course." The 57-year-old al-Megrahi, who is terminally ill with prostate cancer, was freed so that "he could die in his native country," MacAskill said earlier. Al-Megrahi's jubilant welcome by several hundred people at the airport in the Libyan capital Tripoli triggered outrage in both Britain and the United States. -- SPA