Scotland's Justice Secretary is facing demands to make a statement to Holyrood after it was claimed he sent a message to the Lockerbie bomber that he should drop his appeal against conviction to smooth the way for his compassionate release.
The allegations - strongly denied by the Scottish Government - are contained in a new book, Megrahi: You Are My Jury, in which Abdelbaset al-Megrahi claims he was "the innocent victim of dirty politics, a flawed investigation and judicial folly".
A Scottish Government spokesman branded the book, published today, as "third-hand hearsay".
He stated: "We can say categorically that neither the Scottish Government had any involvement of any kind in Mr Al-Megrahi dropping his appeal, or indeed any interest in it.
"That was entirely a matter for Mr Al-Megrahi and his legal team."
But Labour, the Tories and the Liberal Democrats all called for Justice Secretary Kenny MacAskill to make a statement to the Scottish Parliament in the wake of the book's allegations.
Scottish Conservative leader Ruth Davidson said: "This is a staggering claim and implies that the Scottish Justice Minister was offering legal advice to help a convicted killer escape prison."
Scottish Labour's justice spokesman Lewis Macdonald said: "Kenny MacAskill has repeatedly claimed that the decision for al-Megrahi to drop his appeal was 'a matter for him and the courts', yet these extraordinary reports throw all that into question."
The MSP added: "These are very serious allegations. If these reports are true, then Kenny MacAskill will have knowingly misled Parliament. It is only proper that he comes before Parliament as a matter of urgency to spell out exactly what happened at Greenock Prison and in the alleged private meetings with Col Gaddafi's ministers.
"The families of the victims deserve to know whether this secret meeting took place, and if so, exactly what was discussed."
Scottish Lib Dem leader Willie Rennie said: "It is important that the Justice Secretary answers serious questions."
Mr MacAskill took the controversial decision to free the Libyan - the only person convicted of the bombing of Pan Am flight 103 in December 1988 which killed 270 people - on compassionate grounds.
Megrahi, who has terminal cancer, remains alive today despite being said to have three months to live when he was released in August 2009.
Shortly before being freed, Megrahi dropped his second appeal against his conviction.
The book, by writer, researcher and TV producer John Ashton, says Mr MacAskill met a delegation of Libyan officials 10 days before announcing his decision, including foreign minister Abdulati al-Obedi.
In the book, Megrahi claimed: "After the meeting, the Libyan delegation came to the prison to visit me.
"Obedi said that, towards the end of the meeting, MacAskill had asked to speak to him in private.
"Once the others had withdrawn, he stated that MacAskill gave him to understand that it would be easier to grant compassionate release if I dropped my appeal.
"He said he was not demanding that I do so, but the message seemed to me clear.
"I was legally entitled to continue the appeal, but I could not risk doing so. It meant abandoning my quest for justice."
Mr Ashton, who studied the Lockerbie case for 18 years and spent three years as a researcher with the bomber's legal team, said: "Mr Megrahi makes clear in the book that it was made clear to him by the Libyan official who met with Mr MacAskill that it would help his case for compassionate release if he dropped his appeal."
The author added that Megrahi "felt very strongly that dropping the appeal would help his application for compassionate release".
A spokesman for the Scottish Government said the claims in the book were "wrong", and added: "Officials were present at all meetings the Justice Secretary had on this matter at all times."
He said that at the time Megrahi abandoned his appeal he had "no way of knowing" if he would be granted compassionate release, or if his bid to be transferred to a Libyan jail - which was rejected by the Justice Secretary - would be successful.
The spokesman said: "This book amounts to no more than third-hand hearsay."
Mr Ashton said the book contains "new evidence which breaks the chain between the bombing and Mr Megrahi".
He said: "The evidence relates to the timing device that was used in the bomb.
"The court accepted that a fragment of circuit board found at the crash site was part of a timer that was supplied to Libya.
"The new evidence breaks that chain because it demonstrates forensically that that was not the case."
However the Scottish Government spokesman said: "The Scottish Government do not doubt the safety of Mr Al-Megrahi's conviction, (he) was found guilty of an act of state-sponsored terrorism and did not act alone.
"Scotland's justice system has been dealing with the Lockerbie atrocity for nearly 23 years and in every regard the due process of Scots law has been followed - in terms of the investigation, prosecution, imprisonment, rejection of the prisoner transfer application and granting of compassionate release.
"The Justice Secretary released Mr Al-Megrahi on compassionate grounds and compassionate grounds alone, based on the rules and regulations of Scots law and the recommendations of the Parole Board for Scotland, the prison governor and the advice of the Scottish Prison Service director of health and care Dr Andrew Fraser - all of which have also been published."
A spokesman for Prime Minister David Cameron said the book was "yet another reminder that Alex Salmond's government's decision to free the UK's greatest mass murderer was wrong".
However, he added: "Writing a book three years after he was released is an insult to the families of the 270 people who were murdered."
But Mr Ashton described those remarks as "outrageous". He said: "The Prime Minister knows nothing about this case. He should read the book, and if he read the book he would know that this conviction was not safe."