Libya's vice-premier said Monday his country was determined to have Moamer Kadhafi's ex-spy chief, also wanted by the International Criminal Court, extradited to stand trial on home soil.
"We are determined to get (Abdullah) Senussi back, because this man has committed crimes against Libyans," Mustafa Abu Shagur said on his arrival in Mauritania where Senussi was arrested Friday.
"He must answer for these in Libya, before Libyan courts," he said.
Mauritania has received a flurry of extradition requests, with both France and the ICC in The Hague keen on prosecuting Kadhafi's feared former right-hand man.
Interpol has issued a so-called "red notice" for Senussi on behalf of Libya "for fraud offences including embezzling public funds and misuse of power for personal benefit".
Senussi, brother-in-law to the slain dictator Kadhafi and said by some to have been the "black box" of the former Libyan regime, is still in the hands of Mauritanian police.
The country is not party to the treaty that set up the ICC and officials want to carry out their own investigation before it considers any extradition requests.
Senussi was detained Friday night at Nouakchott airport after arriving on a regular flight from Casablanca in Morocco, using a false passport.
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Amnesty international said on Saturday that Senussi should be tried by the ICC in the absence of a functioning judiciary in Libya.
The ICC issued an arrest warrant for Senussi on June 27, saying he was an "indirect perpetrator of crimes against humanity, of murder and persecution based on political grounds" committed in the eastern city of Benghazi.
He could also be held accountable in Libya for the Abu Salim prison massacre of 1996 when more than 1,000 detainees were gunned down.
Mauritanian legal expert Brahim Ould Ebetty warned that the extradition requests would have to be examined by a court and a final decision could "take some time if rules and procedures are followed".
Ebetty said France has "the best argument to make" for extradition.
Senussi faced an international arrest warrant after a Paris court sentenced him in absentia to life imprisonment for involvement in the downing of a French UTA airliner over Niger in September 1989.
The plane was carrying 170 people from Brazzaville to Paris via N'Djamena.
That attack -- along with the bombing of a Pan Am jumbo jet over Lockerbie, Scotland in December 1988, in which 270 people were killed -- led to a UN-mandated air blockade of Libya in 1992.