Muammar Gaddfi's son Saif al-Islam - the only member of the ruling family to remain at large - has been captured as he travelled with aides in a convoy in Libya's southern desert, officials said.
Thunderous celebratory gunfire shook the capital Tripoli as the news spread.
A spokesman for the Libyan fighters who captured him said Saif al-Islam was detained about 30 miles west of the town of Obari with two aides as he was trying to flee to neighbouring Niger.
The International Criminal Court had charged Gaddafi, Saif al-Islam and Libya's former intelligence chief Abdullah al-Senoussi with crimes against humanity for the brutal crackdown on dissent as the uprising against the regime began in mid-February and escalated into a civil war. Saif al-Islam's capture leaves only al-Senoussi at large.
Libyan TV posted a photo purportedly of Saif al-Islam in custody. He is sitting by a bed and holding up three bandaged fingers as a guard looks on.
Mohammed al-Alagi, the National Transitional Council's justice minister, said Saif al-Islam was detained deep in Libya's desert last night by revolutionary forces from the mountain town of Zintan who had been tracking him for days.
Saif al-Islam was being held in Zintan but would be transported to Tripoli soon, according to al-Alagi.
A spokesman for the Zintan brigades, Bashir al-Tlayeb, who first announced the capture at a press conference in Tripoli, said the NTC, which took over governing the country after Gaddafi was removed, would decide where Saif al-Islam would be tried.
He also said that there was still no information about al-Senoussi's whereabouts.
Saif al-Islam Gaddafi, at 39 the oldest of seven children of Muammar and Safiya Gaddafi, had long courted Western favour touting himself as a liberalising reformer in the autocratic regime but then staunchly backed his father in his brutal crackdown on rebels in the regime's final days.
