The head of the FBI and Scotland's top prosecutor have visited Libya to assess the ongoing investigation into the 1988 Lockerbie airliner bombing, Scottish officials said on Wednesday.
The director of the US Federal Bureau of Investigation, Robert Mueller, and Scotland's Lord Advocate Frank Mulholland met Libya's interim prime minister Abdel Rahim al-Kib in Tripoli on April 25.
Scotland's Crown Office and Procurator Fiscal Service said the meeting was kept secret at the time for security reasons.
A spokesman said: "The Lord Advocate, Frank Mulholland QC, and Robert S Mueller, director of the FBI, met with the Libyan prime minister Abdel Rahim al-Kib to discuss the ongoing investigation into the Lockerbie bombing.
"The Libyan authorities confirmed that they fully understood the importance of dealing with the tragic issues left behind by Colonel Kadhafi and his regime, both in Libya and overseas."
In February, the Crown Office said a formal request had been sent to the Libyan government asking for access to the country for police and prosecutors involved in the investigation into the bombing.
The Crown Office said the request was raised in the meeting.
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"The Lord Advocate expressed his desire to the Libyan prime minister that there will be a positive response to his recent request for co-operation and the international letter of request (ILOR)," the spokesman said.
Scottish and US authorities hope that the removal of Moamer Kadhafi's four-decade-long regime will allow investigators to find fresh leads in the probe into the bombing of a Pan Am jet over Lockerbie, Scotland, which killed 270 people.
The Libyan National Transitional Council has previously confirmed to the British government that it will assist the ongoing criminal investigation, and agreed to allow Scottish police officers to travel to Libya.
Abdelbaset Ali Mohmet al-Megrahi, the only person convicted of the bombing, was released from a Scottish jail on compassionate grounds in August 2009 and allowed to return to Libya.
Scottish authorities said at the time their decision was based on doctors' assessments that he had terminal cancer and only had three months left to live, but two and a half years later he remains alive and living in Tripoli.
His brother Abdelhakim al-Megrahi told AFP on April 15 that he had returned home after having a blood transfusion in hospital.
"He is still very very sick, in the final stages of a cancer which has no cure, so his days are numbered," he said.
Most of those killed in the bombing of the London-New York flight were US citizens.