The Scottish Government said Megrahi was released for the right reasons
The release of the Lockerbie bomber has damaged the reputation of Scotland across the globe, former Labour first minister Jack McConnell has warned.
He condemned the move and said it must be made clear it was not done in the name of the Scottish people.
Abdelbaset Ali al-Megrahi was freed from Greenock prison on Thursday to be allowed home to Libya to die.
A Scottish government spokesman said the decision had been reached "on the basis of due process" and "evidence".
The bomber's release - and the hero's welcome he was given on return to Libya - provoked anger from many relatives of those who died aboard Pan-Am flight 103, particularly in the US.
A total of 270 people died when the transatlantic airliner came down over Lockerbie in 1988.
Speaking to BBC Scotland, Mr McConnell said the sight of the Scottish flag being waved as Megrahi arrived back in Libya had brought shame on Scotland.
He said: "The way in which the decision has been made and the decision itself have damaged the reputation of the Scottish justice system - historically our legal system has had a fantastic international reputation.
"It's damaged that reputation, but much more significantly it's also damaged the reputation of Scotland internationally.
"I think it's absolutely vital that the Scottish Parliament now takes action to limit that damage and to give a clear indication to the rest of the world that when the Scottish Government made this decision they were not acting with the support of the people of Scotland."
He said the decision was a "grave error of judgement" and claimed there had been other options for additional compassionate relief without Megrahi being freed.
However, a spokesman for Scottish Justice Secretary Kenny MacAskill, who took the decision to free Megrahi, suggested Mr McConnell was trying to score political points.
"Former First Minister Henry McLeish - who was in office at the time of the Lockerbie conviction - has said that the justice secretary's decision was 'the right decision for the right reasons'," the spokesman said.
"The justice secretary reached his conclusions on the basis of due process, clear evidence, and recommendations from the Parole Board and Prison Governor.
"Now that Mr MacAskill has made his statement, Parliament has requested a recall, and Mr MacAskill is pleased to answer any and all questions which MSPs have. That is the proper parliamentary process.
"The issue has nothing to do with party politics, and any attempt to politicise it is extremely foolish and will backfire spectacularly - particularly on the Labour Party."
Mr McConnell's attack comes the day after the director of the FBI accused Scottish Justice Secretary Kenny MacAskill of having made a "mockery of justice".
'True to values'
Announcing the release on Thursday, Mr MacAskill said the Scottish justice system was based on both judgement and compassion.
"Compassion and mercy are about upholding the beliefs we seek to live by, remaining true to our values as a people - no matter the severity of the provocation or the atrocity perpetrated," he said.
The Scottish Parliament has been recalled and will meet on Monday to discuss the release.
International pressure over the handling of the release and the welcome Megrahi was given in Tripoli have continued to mount.
Cheering crowds, some waving Saltires, greeted his arrival, despite pleas for sensitivity from the US and UK governments.
Colonel Gaddafi has said that Prime Minister Gordon Brown had "encouraged" the Scottish government to take what he called a "courageous" decision, but the Foreign Office has strongly denied claims it was linked to a trade deal between the UK and Libya.
The claim was made by Saif al-Islam Gaddafi, the son of Libyan leader Colonel Gaddafi, who told Libyan TV Megrahi's case was "always on the negotiating table" during talks with the UK on commercial contracts.
Business Secretary Lord Mandelson said such a suggestion was "not only wrong" but "actually quite offensive".