Mauritanian state media has announced that former Gaddafi-aide Abdullah al-Senussi has been extradited to Libya.
"He was extradited to Libya on the basis of guarantees given by Libyan authorities," a Mauritanian government source told Reuters news agency.
Al-Senussi fled Libya during the uprising and was arrested for entering Mauritania illegally.
He is wanted by the International Criminal Court for committing crimes against humanity during his time as spy-chief for Col Gaddafi’s regime, but his extradition to Libya will make a trial at The Hague less likely.
Libya wants to try Al-Senussi for crimes committed while he was Gaddafi’s aide.
He is also wanted by France, who has sentenced him in absentia to life imprisonment for the shooting down of a plane over Niger, which killed 170 people.
Al-Senussi is also accused of involvement in atrocities, including his alleged role in the 1996 massacre of more than 1,000 inmates at the Abu Salim prison in Tripoli.