Two Libyans have been identified as suspects in the ongoing investigation into the Lockerbie bombing, Scottish prosecutors have confirmed.
They believe the two individuals were involved along with Abdelbaset al-Megrahi - the only person to have been convicted of the 1988 atrocity in which 270 people were killed.
Megrahi, who was released from jail by the Scottish Government in 2009 on compassionate grounds after being diagnosed with prostate cancer, died in 2012 protesting his innocence.
Scotland's Lord Advocate Frank Mulholland QC recently met the US Attorney General, Loretta Lynch, in Washington to review progress made in the ongoing investigation.
They have now requested permission from the Libyan authorities for Scottish police and the FBI to interview the two named suspects in Tripoli.
A Crown Office spokesman said: "The Lord Advocate and the US Attorney General have recently agreed that there is a proper basis in law in Scotland and the United States to entitle Scottish and US investigators to treat two Libyans as suspects in the continuing investigation into the bombing of flight Pan Am 103 over Lockerbie.
"The Lord Advocate has today, therefore, issued an International Letter of Request to the Libyan attorney general in Tripoli which identifies the two Libyans as suspects in the bombing of flight Pan Am 103.
"The Lord Advocate and the US Attorney General are seeking the assistance of the Libyan judicial authorities for Scottish police officers and the FBI to interview the two named suspects in Tripoli.
"The two individuals are suspected of involvement, along with Abdelbaset Ali Mohmed al-Megrahi, in the bombing of flight Pan Am 103 in December 1988 and the murder of 270 people."
The Crown Office has not confirmed the names of the two suspects they are seeking to interview.
The ongoing investigation into the bombing remains a joint one between US and Scottish prosecutors, the Police Service of Scotland and the FBI.
The flight was on its way from London to New York when it exploded above Lockerbie, in southern Scotland, on the evening of December 21 1988, killing everyone on board and 11 people on the ground.
Megrahi was found guilty of mass murder following a trial at Camp Zeist in the Netherlands in 2001 and was jailed for life with a minimum term of 27 years behind bars. He lost his first appeal in 2002.
The following year, he applied to the Scottish Criminal Cases Review Commission (SCCRC) for a review of his conviction.
A £1.1 million investigation by the body led to a finding in June 2007 of six grounds where it believed a miscarriage of justice may have occurred.
This decision opened the door to Megrahi's second appeal against his conviction. Although a number of hearings had already been held before senior appeal judges, he dropped his appeal two days before being released from prison in August 2009.
Earlier this year, Scottish judges ruled relatives of the victims of the Lockerbie bombing should not be allowed to pursue an appeal on Megrahi's behalf.
The group of British relatives had argued they had a ''legitimate interest'' in trying to get his case back before a court for a full appeal.
The SCCRC had asked the Appeal Court in Edinburgh for guidance on whether members of the victims' families could take such a legal move forward.
But judges ruled in July that the law was ''not designed to give relatives of victims a right to proceed in an appeal for their own or the public interest''.