Libya's interim prime minister, Abdel Rahim al-Kib, said: "I reassure our people and the world that Saif, and those with him, will be given a fair trial in which international rights and norms will be guaranteed. The judicial authorities will communicate with the International Criminal Court to examine where Saif al-Islam must be tried. Any co-operation with international institutions is welcome," he said, implying they would like him to be tried in Libya.
The ICC said Libya had an obligation to surrender Saif but did not exclude the possibility of a trial in Libya. "The Libyan authorities have an obligation to co-operate with the court, including with respect to the arrest and surrender of Saif al-Islam to the court as indicated in the UN's resolution," ICC spokesman Fadi El-Abdallah said. "If Libyan authorities believe that a trial at national level is a better solution, they can ask that the case not be admitted in The Hague, based on the court's complementary principle. If they want a trial in Libya, they must submit a request for dismissal and procedures in Libya must be conducted on the same charges as those contained in the warrant of the ICC."
Video footage, shown on Libyan television and distributed by the country's transitional authority, pictured Gaddafi wrapped in a brown blanket and lying on a mattress. He was holding up three heavily bandaged fingers from injuries sustained in a Nato bombing raid a month ago as he fled from Bani Walid the day before his father's death.
The late Muammar Gaddafi's heir-apparent was looking thinner and had allowed the hair to grow on his usually shaven head; he had also grown a beard. News of his capture was greeted by celebratory gunfire in Tripoli.
Britain, France and the United States all called on Libya's new rulers to work with the ICC. The French Foreign Ministry said: "We have renewed our call for the NTC to fully co-operate with the ICC and to ensure that Saif al-Islam gets a fair trial.
"We trust that the Libyan authorities and the ICC will ensure that justice runs its course, so that the new Libya can be built on the rule of law and respect for human rights," Nato spokeswoman Oana Lungescu said.
Ahmed Ammar, one of Saif's captors, said his unit of 15 men in three vehicles, acting on a tip-off, had intercepted two cars carrying Saif and four others near the small oil town of Obari on Saturday.
After the fighters fired into the air and ground in order to halt the cars, they asked the identity of the travellers. The man in charge replied that he was "Abdelsalam" - meaning "servant of peace". But the fighters quickly recognised him as Saif and seized him without a fight.
"At the beginning he was very scared. He thought we would kill him," Ammar said.Bashir Thaelba, a Zintan commander, told reporters in the capital that Saif would be held in Zintan until there was a government - due to be formed within days - to whom he could be handed over.
Saif, 39, who studied at the London School of Economics, was once regarded as the reform-minded and pro-Western face of the regime. He gained notoriety early in the war when he delivered a bloodthirsty 40-minute television statement to Libyans warning that the regime planned to "eradicate" its enemies."
He was wanted on an international warrant from the ICC for crimes against humanity, including his indirect involvement in the deaths of opponents of his father's regime, charges he rejected. Saif and former intelligence chief, Abdullah Senussi, were the last two senior figures to be sought by the new government.
DEAD
Colonel Muammar Gaddafi
The longest-serving leader in Africa and in the Arab world. Killed on October 21 after capture in the town of Sirte, his birthplace, after fierce fighting between a small band of loyalists and NTC forces.
Mutassim Gaddafi
A former national security adviser and member of his father's inner circle, Mutassim was killed fighting alongside Gaddafi in Sirte on October 21. His body, identified by NTC officials, was later shown on Libyan TV.
Saif al-Arab Gaddafi
According to Libyan reports, army officer Saif al-Arab, one of Gaddafi's youngest sons, was killed along with three of Gaddafi's grandchildren in a Nato air strike on the Gaddafi compound on May 1.
CAPTURED
Saif al-Islam Gaddafi
Arrested on Saturday, Gaddafi's heir apparent until the uprising was discovered in Libya's southern desert with several bodyguards trying to escape to Niger. He had evaded capture since the fall of Sirte.
FledSafia al-Gaddafi, Muhammad, Hannibal and Ayesha Gaddafi
Gaddafi's second wife and the mother of seven of his children, Safia is believed to have fled to Algeria with three Gaddafi children after the rebels' capture of Tripoli.
Saadi Gaddafi
The former president of the Libyan football federation and Libyan team captain, Saadi, who had a brief playing career in Italy's Serie A division, has been given refuge in neighbouring Niger.
UNKNOWN
Khamis Gaddafi
Gaddafi's son and the former commander of the feared 32nd Brigade, who received military training in Russia, has reappeared several times to defy reports of his death during the uprising. It is not known if he is now dead or just in hiding.
- OBSERVER, AFP