Colonel Gaddafi's son Saif al-Islam has been captured, Libyan officials say.
He was taken by fighters near the southern town of Obari and flown to the city of Zintan in the north. Saif al-Islam told a journalist he was well.
He is the last key Gaddafi family member to be seized or killed. Libya's new prime minister says he will get a fair trial in Libya.
Saif al-Islam, 39, is wanted by the International Criminal Court (ICC) for alleged crimes against humanity.
A militia force allied to the ruling National Transitional Council (NTC) said he had been captured in the desert about 50km (30 miles) west of Obari, and taken to their base in Zintan in the north.
A commander of the Zintan militia, Wisam Dughaly, said Saif al-Islam had been captured along with several aides as they tried to smuggle him out to neighbouring Niger.
Fighters said they were taken without a shot being fired.
"At the beginning he was very scared. He thought we would kill him," one of his captors, named as Ahmed Ammar, told Reuters news agency.
Asked by a Reuters reporter Marie-Louise Gumuchian on the flight to Zintan if he was feeling all right, Saif al-Islam said simply: "Yes."
He told her he had been injured in a Nato air strike about a month ago.