US private equity giant Carlyle is in talks to acquire Libya's state-controlled oil refining and marketing operation, Tamoil.

Al-Saadi Gaddafi, the son of Colonel Muammar Gaddafi, the country's long-time leader, said Carlyle was one of four or five groups involved in an international tender to buy 100 per cent of Tamoil. It is thought the business will fetch close to €3bn (£2bn).

Mr Gaddafi added that the other candidates included groups from Poland, Hungary and the United Arab Emirates. In addition, he said the Italian energy group ERG might have "increased their bid a little bit. So maybe they will come back."

Neither ERG nor Carlyle would comment.

Tamoil was acquired by Oilinvest, Libya's foreign oil investment arm, in 1988. It refines, markets and sells the country's oil, and has around 3,000 petrol stations in Italy, Germany, the Netherlands, Switzerland and Spain, with a further 150 in Africa.

The Washington DC-based Carlyle has been known in the past for its links to prominent right-wing US politicians. These include the former US secretary of state James Baker and the former US defense secretary Frank Carlucci, as well as the former British prime minister John Major. None of the men retains positions with the company.

Carlyle, which has concentrated on energy and defence companies, is in the process of raising a new fund. If successful, it will become the world's largest private equity group, ahead of Kohlberg Kravis Roberts, Texas Pacific and Blackstone.

The sale of Tamoil would mark a change of direction for Libya, which has used the business to expand its international downstream operations.

It could also have implications for Juventus, the Italian football club recently relegated to Serie B after a high-profile match-fixing scandal. Tamoil became the club's shirt sponsor last year after agreeing a potential 10-year, €240m deal with Oilinvest.

The sponsorship is one of the most valuable of its kind in Europe, but it remains to be seen whether any new owner of Tamoil would wish to maintain it in the long term. Juventus already faces a probable cut in revenues because of its relegation. Mr Gaddafi confirmed that the club would be asked for a reduction.

However, he cautioned that it was not out of the question that Libya might retain a stake in Tamoil and could change its current plans to sell 100 per cent. Asked when the process would conclude, he replied: "They said they would do it very soon, but I don't know exactly."