The trial of Baghdadi al-Mahmoudi, Libya's last premier of the Muammar Gaddafi era, was due to open on Monday in the Tripoli.
Al-Mahmoudi faces charges of involvement in crimes under the Gaddafi rule, which was toppled in 2011, said the spokesman for chief prosecutor Taha Baara.
He served as prime minister from 2006 until August 2011, when he fled to Tunisia after insurgents seized control of Tripoli, virtually ending Gaddafi's 42-year rule.
Tunisia extradited al-Mahmoudi to Libya in June amid criticism from human rights groups that he could be subjected to abuses and would not receive a fair trial at home.
Libya's new rulers have repeatedly pledged to provide al-Mahmoudi, now in his sixties, with a fair and free trial. - Sapa-dpa