Chief of US Federal Bureau of Investigation (FBI) Robert Mueller has criticised the release of Abdelbaset Ali al-Megrahi, the Libyan national, who was responsible for the bombing of hundreds of people over Lockerbie, by Scottish government on compassionate ground.
In a letter, Robert Mueller described the decision to relase the bomber "a mockery of justice" and said it has given "comfort to terrorists around the world".
Abdelbaset Ali al-Megrahi, despite being responsible for the bombing and killing over 270 people over Lockerbie in Sctoland in 1988, has received a hero's welcome in Libya.
In a letter sent to Scottish Justice Secretary Kenny MacAskill, FBI Director Robert Mueller wrote: "Your action in releasing Megrahi is as inexplicable as it is detrimental to the cause of justice. Indeed your action makes a mockery of the rule of law.
"Your action gives comfort to terrorists around the world."
The 57 year old Megrahi is said to be terminally ill with prostate cancer. He was freed by Scottish Justice Secretary Kenny MacAskill, on compassionate grounds.
However, the Scottish government has said that "it had consulted widely in the US and UK and had made the right decision."
Megrahi was found guilty of 270 counts of murder in 2001. He was given a life sentence.
According to the BBC, Scotland's First Minister Alex Salmond has said releasing the Lockerbie bomber was the "right decision", as criticism mounts from both sides of the Atlantic.
Supporting the statement of the FBI chief, Scotland's former first minister Jack McConnell has said it is a "grave error of judgment".
Mr Salmond said: "We didn't do it to court popularity." He is quoted as saying by the BBC "We did it because it was the right thing to do in terms of the Scottish justice system."
He said Scotland had a "strong" and "enduring" relationship with the US, but it did not "depend on us always coming to agreement".
"We understand the upset. We understand the disagreement. But we have to do what is right in terms of our legal system, that is what we are duty-bound to do," he said.
"No-one, I think, seriously believes that we made any other decision except for the right reasons," he added.
Alex Salmond said : "The way in which the decision has been made and the decision itself have damaged the reputation of the Scottish justice system."
"Much more significantly it's also damaged the reputation of Scotland internationally."
According to the BBC on Saturday, Libyan TV showed pictures of Col Gaddafi meeting Megrahi and praising "my friend" Gordon Brown and the British government for what he said was their part in securing his freedom.
Jack McConnell said that the scenes in Libya had "damaged the reputation of Scotland"