The International Criminal Court's prosecutor and his deputy have arrived in Libya following the weekend arrest of Muammar Gaddafi's son Saif al-Islam. The late Libyan leader's son is wanted for alleged war crimes by the ICC. The ICC team is to discuss whether he will be tried at The Hague or in Libya, as the interim government has indicated it would prefer. The visit comes as a new cabinet is expected to be announced, three months after Col Gaddafi was overthrown. It will be the first step to forming an elected government - the transitional authority is tasked with drafting a constitution and holding democratic elections. Prime Minister-designate Abdurrahim al-Keib said all of Libya's regions would be represented. Mr Keib was elected prime minister by the National Transitional Council (NTC) last month. The NTC is a coalition of rival factions that came together to oust Col Gaddafi, who was killed in his birthplace, Sirte, on 20 October. 'ICC will decide' ICC chief prosecutor Luis Moreno-Ocampo and his deputy, Fatou Bensouda, are leading a delegation which will meet Libya's new authorities. It is part of co-ordination efforts following the capture of Saif al-Islam on Saturday as he was reportedly trying to flee to neighbouring Niger. The ICC has also issued an arrest warrant for Col Gaddafi's spy chief Abdullah al-Sanussi, who was regarded as the late leader's right-hand man - and one of the regime's most-feared figures. Libya's government says Mr Sanussi, a brother-in-law of Col Gaddafi, was arrested at his sister's home in the southern town of Sabha on Sunday. "The issue of where the trials will be held has to be resolved through consultations with the court. In the end, the ICC judges will decide, there are legal standards which will have to be adhered to," said Mr Moreno-Ocampo. "Their arrest is a crucial step in bringing to justice those most responsible for crimes committed in Libya. This is not a military or political issue, it is a legal requirement," he said. Saif al-Islam had been on the run since NTC forces took Tripoli in August, six months into the uprising. Mr Keib has promised that Saif al-Islam would receive a fair trial after concerns were raised about the possibility of ill-treatment given the killing of Col Gaddafi after his capture in Sirte. 'Competence' On Monday, Mr Keib said he was finalising his cabinet with the NTC and expected to announce the line-up on Tuesday. "We will use competence as a basic measure and this way we will be able to include all of Libya's regions," he told a news conference. An NTC source quoted by Reuters news agency said the local military commander in the western town of Zintan, Osama al-Juwali, had been designated defence minister. Libya's deputy UN ambassador Ibrahim Dabbashi had been named foreign minister, interim oil minister Ali Tarhouni was moved to finance and oil industry executive Hassan Ziglam was taking over the oil ministry, Reuters said, but those names have not been confirmed. The BBC's Rana Jawad, in Tripoli, says the first test of the new government will be to successfully centralise Libya's political and military powers. Only then will the government be able to proceed with drafting a constitution and eventually hold Libya's first democratic elections in its modern history, our correspondent says. Col Gaddafi was overthrown and his supporters defeated after a nine-month insurgency that began in the eastern town of Benghazi and eventually swept across the rest of the country. Militias in different areas, joined by defectors from the army, were aided by Nato forces who bombed Col Gaddafi's forces under a UN mandate to protect civilians.