A Lebanese security official says members of a Libyan fact-finding mission who came to Beirut to investigate the case of a detained son of their country's late dictator Moammar Gadhafi have left amid security concerns.

The official says authorities advised the Libyan Justice Ministry delegation to leave Lebanon after relaying an unspecified threat to its safety. The delegation left Lebanon on Tuesday.

The official did not elaborate. He spoke on condition of anonymity in line with regulations.

Hannibal Gadhafi remains in Lebanese custody after unknown captors delivered him to authorities earlier this month. He is being questioned about the disappearance of top Shiite cleric Moussa al-Sadr while on a visit to Libya in 1978.

The Libyan delegation came to request Gadhafi's extradition for crimes committed during his father's rule.