Willie Rennie, who is also demanding the Crown Office demonstrates the 1988 atrocity is still being investigated, said recent comments by Mahmud Nacua, the Libyan ambassador to the UK, that Tripoli would release material added fuel to his demands for a public inquiry.
Abdelbaset Ali Mohmed al Megrahi, who was found guilty of 270 counts of murder, had won the right to appeal his conviction but gave up the legal challenge as part of the requirements of his early release from prison in 2009. He died in May last year at home in Tripoli.
Mr Nacua said documents relating to the atrocity would be released as soon as time, security and stability permitted.
He said: "All files will be open and everyone will know what happened."
Mr Rennie said: "A week after the Libyan Government has said it is prepared to release all its files in relation to the Lockerbie bombing, Scottish Liberal Democrats have still not had a response to our demands for a public inquiry into the Lockerbie prosecution.
"I can see no reason why we can't go ahead with that now. The First Minister has the opportunity to shine a light on to the conduct of the Crown Office, which for years has been left blemished by the six separate grounds of appeal identified by the Government's own Scottish Criminal Cases Review Commission [SCCRC].
"On matters that relate to the integrity, fairness and justice of the Scottish justice system, it is simply not good enough to leave this to a family in Tripoli."
But a Scottish Government spokesman said: "Issues relating to the conviction of Mr al Megrahi must be a matter for a court of law – he was convicted in a court of law, his conviction was upheld on appeal, and that is the only appropriate place for his guilt or innocence to be determined.
"It remains open for relatives of Mr al Megrahi to ask the SCCRC to refer the case to the Appeal Court, which ministers would be entirely comfortable with.
"The Lockerbie case remains a live investigation, and Scotland's criminal justice authorities have made clear that they will rigorously pursue any new lines of inquiry."
Megrahi was sentenced to life in prison for the 1988 bombing of a US airliner over the Dumfries and Galloway town, which claimed 270 lives.
He was later diagnosed with cancer and released from prison on compassionate grounds in August 2009.
Mr Rennie wrote to the Lord Advocate in August seeking assurances the Lockerbie bombing was still being "rigorously and actively investigated".
The Crown Office said: "We can confirm the Lord Advocate has met the Libyan Prime Minister on two occasions, once in Tripoli and later in London. Since the meeting, the Libyan PM has been provided with the information he requested on a number of issues relating to the conduct of the proposed investigation in Libya.
"The Lord Advocate has recently written to the new Libyan PM and the Foreign Office, at the request of the Crown, is in contact with the Libyan Government to progress the request for Scottish police officers to travel to Libya for inquiries into the involvement of others in this act of state-sponsored terrorism."