Ministers believe there was no reason to open an investigation. Meloni supporters accused Rome's chief prosecutor of politicising the case and say it is part of a broader battle pitting magistrates against the government over planned judicial reform that will shake up Italy's creaking legal system.

Migrants expressed their dismay and sense of betrayal on Wednesday over Italy's decision last week to release a Libyan policeman wanted by the International Criminal Court (ICC) for war crimes and human rights abuses and allow him to return home.

Prime Minister Giorgia Meloni of Italy announced on Tuesday that she was being investigated by Italian prosecutors for her alleged role in aiding and abetting the release last week of a Libyan official wanted on war crimes charges.