A delegation led by Scotland's Lord Advocate Frank Mulholland QC held "extremely positive" meetings with senior members of the Libyan Congress and the UK and US ambassadors.
The visit to Tripoli this week followed last month's announcement by the Libyan Attorney General that he had appointed two prosecutors to the case.
For the first time they met Scottish and US investigators who are trying to establish whether there are other individuals in Libya who could be brought to trial for involvement in the attack.
Libyan Abdelbaset Ali Mohmed al Megrahi is the only person to have been convicted of the bombing of Pan Am flight 103 over Scotland, in which 270 people were killed.
Mr Mulholland said: "The meetings were extremely positive and there is a commitment on behalf of the Libyan authorities to work with both Scotland and the United States to progress the investigation.
"Information has been provided to the Libyan prosecutors to assist them in their understanding.
"It was agreed that there will be regular meetings to assess developments and progress."
Megrahi, given a life sentence in 2001, was controversially released from jail by the Scottish Government in August 2009 after being diagnosed with prostate cancer.
He died protesting his innocence in Tripoli in 2012.
Since the fall of the Gaddafi regime in 2011, British investigators have visited the country to try to uncover new evidence.
Despite the guilty verdict and Megrahi's decision to drop a subsequent appeal against conviction, politicians, campaigners and families of victims are still dealing with the impact, with some of the British relatives considering another appeal against his conviction. Megrahi's family have also indicated they plan to appeal against the conviction.