Libya's new rulers, under pressure from human rights groups, have vowed to put on trial Moamer Kadhafi's former spy chief before June elections if Mauritania extradites him as expected.
Fathi Baaja of the National Transitional Council said that trials of Kadhafi loyalists have so far lagged in Libya due to inadequate prison infrastructure and a paralysed judiciary.
"If Abdullah Senussi is extradited to Libya, his trial and that of (Kadhafi son) Seif al-Islam will be held in the near future and before the general election" scheduled for June, said Baaja.
"The preparations are now on track," he said.
Mauritania said Wednesday it has yet to make a decision on the extradition of Senussi, who was arrested at Nouakchott airport last week and is also wanted by France and the International Criminal Court.
Earlier, the Libyan government said his handover was a done deal after meetings with Mauritanian President Mohamed Ould Abdel Aziz.
In a statement to AFP, Libya's interim prime minister, Adbel Rahim al-Kib, said the authorities "will start trials of officials of the old regime as soon as possible."
"We reassure the people of Libya and the international community that Libya will soon judge those who committed crimes against the people," said Kib, adding they would be guaranteed fair trials.
In a mobile phone message, general prosecutor Abdelaziz al-Hasadi called on Libyans to give evidence on allegations against former Kadhafi regime officials and collaborators for them to be brought to justice as soon as possible.
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Tripoli has come in for strong criticism from international human rights groups for the way its justice system is dealing with Kadhafi loyalists, including accusations of prisoners being tortured.
Several officials of the ousted regime and hundreds of loyalists, both military and civilians, have languished for months in prison, many of under the control of armed brigades that fought the regime.
"More than 3,000 Kadhafi supporters are in the prisons of Misrata where they are awaiting trial," said Suleiman al-Fortia, the NTC's representative in the western city.
Senussi is wanted by the International Criminal Court for crimes against humanity allegedly committed during last year's revolt that ousted Kadhafi. Seif al-Islam, the late strongman's most prominent son, has been held in Libya since his arrest in November.
Ahmed Jehani, Tripoli's representative at the ICC, said The Hague-based court has been putting "pressure on Libya to begin the trial of Seif al-Islam or to hand him over" to the tribunal.
NTC Vice President Aknan Salem said that, for safety reasons, the authorities wanted to ensure they had the facilities that could serve as both a prison and court.
"We are now able to equip two locations in Tripoli and (the eastern city of) Benghazi where Kadhafi's loyalists will be transferred," he said.
At the same time, the authorities were also trying to close the net around fugitive Kadhafi family members and former officials of his regime, said Aknan.
"We are issuing arrest warrants against fugitives and asked all the brotherly and neighboring countries ... to deliver them to us," he added.
Libya's general prosecutor has sent his counterpart in Cairo a list of Kadhafi loyalists wanted by his office and thought to have taken refuge in Egypt, which says it has begun negotiations for their handover.