Trials of Qaddafi loyalists have so far lagged in Libya because of an inadequate prison infrastructure and a paralysed judiciary, said Fathi Baaja, of the National Transitional Council.
If Abdullah Al Senussi "is extradited to Libya, his trial and that of [Qaddafi's son] Saif Al Islam will be held in the near future and before the general election" scheduled for June, Mr Baaja said.
"The preparations are now on track."
Mauritania said on Wednesday it has yet to make a decision on the extradition of Al Senussi, who was arrested at Nouakchott airport last week and is also wanted by France and the International Criminal Court.
That came after the Libyan government, also on Wednesday, said his handover was a done deal after meetings with the Mauritanian president, Mohamed Ould Abdel Aziz.
Libya's interim prime minister, Adbel Rahim Al Kib, said yesterday that 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 Mr Al Kib, adding they would be guaranteed fair trials.
Libya's general prosecutor, Abdelaziz Al Hasadi, sent out a nationwide text message yesterday calling on Libyans to give evidence on allegations against former Qaddafi regime officials and collaborators.
Tripoli has been criticised by international human rights groups for the way its justice system has dealt with Qaddafi loyalists, including accusations torture. 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. Saif Al Islam, Qaddafi's son, has been held in Libya since his arrest in November.
Ahmed Jehani, Tripoli's representative at the International Criminal Court, said the court has been putting "pressure on Libya to begin the trial of Saif Al Islam or to hand him over" to the tribunal.
Al Senussi is also wanted by the ICC for crimes against humanity allegedly committed during last year's revolt that ousted Qaddafi.
He was one of six Libyans sentenced to life in prison in 1999 in France for the bombing of a passenger jet over Niger in 1989 that killed 170 people. Paris asked last year that Al Senussi be returned to France when captured.
The backlog in Libya's judicial system stems from a lack of facilities, said Aknan Salem, the NTC vice president. He said 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 in Benghazi where Qaddafi's loyalists will be transferred," he said.
At the same time, the authorities were also trying to capture fugitive Qaddafi family members and former officials of his regime, said Mr Aknan.
"We are issuing arrest warrants against fugitives and asked all the brotherly and neighbouring countries ... to deliver them to us."
Libya's general prosecutor has sent Cairo a list of Qaddafi loyalists wanted by his office and thought to have taken refuge in Egypt, which says it has begun negotiations for their handover.