Mustafa Mohamed Abdel-Jalil formed the government in the eastern city of Benghazi on Saturday, Reuters cited Libya's Quryna newspaper as reporting.
"Muammar Gaddafi alone bore responsibility for the crimes that have occurred in Libya," the paper quoted the former Libyan justice minister as saying.
Libya is bracing for more violence as thousands of pro-democracy protesters, seeking the ouster of the Gaddafi regime, are moving toward the capital, Tripoli.
But foreign mercenaries and troops still loyal to Gaddafi are making every effort to crush the revolution.
The 68-year-old Gaddafi and four of his sons, Saif al-Islam, al-Saadi, al-Mutassim, and Khamis, are reportedly in the Bab al-Azizia military barracks, located west of Tripoli, and fighting against the protesters.
His fifth son, Saif-al-Arab Gaddafi, has joined the revolutionaries, and the Libyan dictator's cousin, Ahmed Qadhaf al-Dam, who was one of the members of Gaddafi's inner circle, has defected to Egypt.
According to the latest reports, demonstrators have already passed through the suburbs of the city.
Tripoli is a strategically important city and home to two million of Libya's more than six million people.
Libyan security forces have reportedly killed over 1,000 people during the recent demonstrations against Gaddafi's four decades of repressive rule.