Details of the alleged confession were first made public five years ago, after the US department of justice announced it was charging Mas’ud over the Lockerbie bombing.
A criminal complaint summary compiled by the FBI claimed he had admitted playing a key role in the attack when he was in detention in 2012, following the collapse of Colonel Gaddafi’s regime the previous year.
The FBI has said the Libyan official who noted Mas’ud’s confession in 2012 is prepared to give evidence at his trial.
Of the 259 passengers and crew who died on board the airliner, 190 were from the United States, where the Mas’ud case will be tried.
The only Lockerbie trial so far took place between May 2000 and January 2001, when three Scottish judges convicted Libyan intelligence agent Abdulbasset al-Megrahi of playing a key role in the plot.
Megrahi was jailed for life but released on compassionate grounds by the Scottish government in 2009 after he was diagnosed with terminal cancer. He died three years later at home in Tripoli.