Lam Magok, a migrant from South Sudan, alleges that he was imprisoned in a Tripoli detention centre run by Osama Almasri Najim -- who is wanted by the International Criminal Court (ICC) on charges including murder, rape and torture.

Najim was detained in the northern Italian city of Turin on January 19 on an ICC warrant, only to be released and flown home to Tripoli on an Italian air force aeroplane two days later.

Magok's complaint alleges that he and other migrants were beaten and kicked by the police chief and his guards.

It names Prime Minister Giorgia Meloni and two senior ministers for "aiding and abetting" Najim, according to a statement from migrant advocacy group Baobab Experience, which is supporting his case.

The complaint filed in Rome could prompt an investigation from prosecutors.

"The Italian government has made me a victim twice, nullifying the possibility of obtaining justice... for all the people, like me, who survived his violence," said Magok in the statement.

Meloni's government did not immediately reply to a request for comment or confirmation.

- Forced to remove dead bodies -

Najim's repatriation has caused a major political row in Italy, and a special court is considering an investigation into Meloni, Justice Minister Carlo Nordio and Interior Minister Matteo Piantedos for their roles in the Libyan's release.

Meloni has called the probe politically motivated.

In a press conference at parliament last week, Magok said he and other migrants were beaten when they tried to flee Tripoli's Mitiga detention centre run by Najim.

The police chief "beat us, tortured us for days", said Magok, according to Italian news agency Ansa, adding that he was forced to remove dead migrants' bodies.

"It was something that I will never forget and it is unthinkable that one might be forced to do this. We want justice," he said.

Najim was freed after an Italian appeals court ruled that he could not be detained in jail due to a technicality involving Nordio failing to respond in time to the ICC request -- which Magok called "clearly functional to Almasri's release".

Magok's lawyer, Francesco Romeo, said that Nordio's failure to act was in "blatant" violation of Italian law.

Moreover, an ICC official statement ahead of Najim's arrest proves that Italian authorities had been informed of the warrant and were involved in a "preventive consultation and coordination activity" related to it, Romeo said in the statement.

For his part, Piantedosi claimed the government had no choice but to repatriate Najim because he was considered too dangerous to remain in Italy.

Meloni has also defended the expulsion of the Libyan police chief, asking why the ICC only issued the warrant as he entered Italy after "spending a dozen calm days in three other European countries".