Italian Prime Minister Giorgia Meloni says she has been placed under judicial investigation over Italy's surprise release of a Libyan citizen who had been wanted for war crimes by the International Criminal Court (ICC).

The government attributed the release to procedural reasons. But critics say it is because Italy depends on Libya to stem the flow of migrants from Africa.

Italy's prime minister on Saturday addressed growing criticism of the repatriation of a Libyan warlord wanted by the International Criminal Court, as Giorgia Meloni cited an appeals court order and security concerns.