Officials in the west African country of Mauritania said they have arrested Abdullah al-Senussi, the former feared intelligence boss of Libya's Moammar Gadhafi.
Senussi, 63, Gadhafi's brother-in-law and among his closest aides, was detained at the airport in Nouakchott, the capital.
Nicknamed “the butcher,” Senussi was one of the last senior Gadhafi officials still at large.
Mauritanian security officials said Senussi arrived by plane from Morocco carrying a false Malian passport.
The arrest was conducted in a joint operation with French officials. France's president Nicolas Sarkozy said he will seek to extradite Senussi.
In 1989, a French court sentenced Senussi to life imprisonment (in absentia) for his role in the bombing of a French airplane that killed 170 people.
Authorities in Libya have confirmed Senussi's capture, BBC reported.
Libya is also seeking his extradition.
The International Criminal Court (ICC) had issued an arrest warrant for Senussi last year on suspicion of having carried out crimes against humanity. The former spy chief is believed to have fled Libya after Gadhafi was killed last October.
The ICC wants to try Senussi in The Hague in Netherlands.
However, since Mauritania is not a signatory to ICC's statue, Senussi's fate is unknown.
Meanwhile, according to reports, Mauritanian intelligence has taken custody of Senussi and are likely to interrogate him about the inner workings of the Gadhafi regime.
Al Jazeera's correspondent in Mauritania, Mohammed Fadel, said: In a short, brief statement, the authorities did not give any more information on Senussi. No one knows exactly how the authorities are going to cooperate with Libya or the ICC, mostly because Senussi has not been charged with any crime in Mauritania.
Senussi himself was particularly brutal – among other atrocities, he was believed to be directly responsible for the massacre of 1,200 political prisoners at the Abu Salim prison in 1996. He also conducted purges of Gadhafi opponents in the 1980s and 1990s.
There had been a number of previous false reports of Senussi's capture and/or death.