"My message to the British and Scottish communities is that I will put out the evidence and ask them to be the jury," he said, refusing to elaborate.
Asked who carried out the bombing of Pan Am Flight 103 which killed 270 people, he replied: "It is a very good question but I am not the right person to ask."
The former intelligence agent, who is suffering from advanced prostate cancer, was released from prison in Scotland on compassionate grounds.
He returned to his native country on Thursday, greeted by hundreds of cheering Libyans.
He also met with Muammar Gaddafi, the Libyan leader, who praised the Scottish authorities for their "courage" to release him from prison
"At this moment I would like to send a message to our friends in Scotland, the Scottish Nationalist Party, the Scottish prime minister ... and I congratulate them on their courage and for having proved their independence despite the unacceptable and unreasonable pressures they faced," Libya's official news agency Jana quoted Gaddafi as as saying.
Britain described celebrations in Libya upon al-Megrahi's return as being "deeply distressing" and Barack Obama, the US president, called the warm welcome "highly objectionable".
Senior US officials said that al-Megrahi's early release could disrupt diplomatic relations between Washington and Tripoli.
Many families of the victims in the bombing have expressed anger that he was released after serving only eight years of a minimum 27-year sentence.
Four years after al-Megrahi's conviction in 2001, Libya admitted responsibility and paid about $2.7bn in compensation to the families of those killed.
The move prompted the lifting of international sanctions against Libya and led to a restoration in diplomatic ties between Tripoli and the West.