British Prime Minister Gordon Brown reportedly discussed details on conditions for the release of convicted Lockerbie bomber Abdel Baset al-Megrahi with Libyan leader Colonel Muammar al-Qaddafi nearly six weeks ago.

A letter sent from Brown's office to Qaddafi on the day al-Megrahi was released asked that the return of the Libyan convicted of killing 270 people in the 1988 Pan Am bombing be kept low key out of concern for his victims and their families, the Guardian reported.

The letter also refers to a conversation between the two leaders at the G8 summit in Italy six weeks ago where Brown writes that he "stressed that, should the Scottish executive decide that Megrahi can return to Libya, this should be a purely private family occasion," the Guardian reported.

The letter, addressed "Dear Muammar," contradicts previous claims that the Lockerbie case was only briefly mentioned during that conversation in July and that Brown stressed it should be left to the Scottish government, the Guardian reported.

A second letter written by the British Foreign Office minister to Libya also confirmed to Scottish Justice Minister Kenny MacAskill that there were no legal reasons to prevent Megrahi's release and expressed hope that MacAskil "consider the Libyan application," the paper reported.

Qaddafi raised eyebrows when he welcomed Megrahi back to Libya Thursday amid a cheering crowd and thanked not only "friends in Scotland, the Scottish National Party, and Scottish prime minister, and the foreign secretary," but also "friend Brown, the Prime Minister of Britain, his Government, the Queen of Britain, Elizabeth, and Prince Andrew, who all contributed to encouraging the Scottish government to take this historic and courageous decision, despite the obstacles."

British Shadow Foreign Secretary William Hague has renewed calls for all official records of conversations about the release to be made public, the Guardian reported.

Meanwhile, the highest ranking Scottish official fired back at criticism from FBI Director Robert Mueller, who called the release of Megrahi a "mockery' of justice."

The head of Scotland's government said Sunday that FBI director Robert Mueller was wrong to criticize the decision to free the Pan Am Flight 103 bomber — insisting there was public support for the release on compassionate grounds.

Al-Megrahi was released because he is terminally ill with prostate cancer and has returned to his native Libya to die.

The release was met with outrage by families of the U.S. victims of the bombing and criticized by President Obama as "highly objectionable."

In a letter to Scotland's government, Mueller said that al-Megrahi's release would give comfort to terrorists all over the world.

"Your action," he wrote, "makes a mockery of the grief of the families who lost their own on December 21, 1988."

Scottish First Minister Alex Salmond told BBC Radio that Mueller was wrong in assuming that all those affected by the bombing were opposed to al-Megrahi's release.

"I understand the huge and strongly held views of the American families, but that's not all the families who were affected by Lockerbie," Salmond said. "As you're well aware, a number of the families, particularly in the U.K., take a different view and think that we made the right decision."

The explosion of a bomb hidden in the cargo hold of a Pan Am flight over Lockerbie, Scotland, killed all 259 people on the plane and 11 on the ground in Britain's worst terrorist attack.

Some bereaved relatives in Britain dispute al-Megrahi's 2001 conviction, and a 2007 Scottish judicial review of his case found grounds for an appeal. He was convicted largely on the evidence of a Maltese shopkeeper, who identified al-Megrahi as having bought a shirt — scraps of which were later found wrapped around the bomb.

Al-Megrahi has maintained his innocence, but last week dropped his appeal so he could be released on compassionate grounds.

Both the British and Scottish governments have denied that they struck a deal with Libya to free the Lockerbie bomber in return for greater access to the country's oil and gas.

"No one I think seriously believes we made any other decision except for the right reasons," Salmond said. "I think it was the right decision. I also absolutely know it was for the right reasons."

He said al-Megrahi's release was consistent with Scotland's legal system, which allows for the release of prison inmates who are terminally ill.

Click here to read more on this story from The Guardian.

The Associated Press contributed to this report.