Judges at the International Criminal Court are investigating whether Italy's release of a Libyan military officer wanted for war crimes by the tribunal breaches the court's statute, a court spokesperson said on Monday.

Italian police arrested Ossama Anjiem, also known as Ossama al-Masri, last month but rather than extraditing him to the Netherlands, where the ICC is based, sent him back to Libya aboard an Italian military aircraft.

The International Criminal Court (ICC) is probing Italy's release of Osama Elmasry Njeem, a Libyan officer wanted for war crimes. His release after arrest in Italy has ignited political outrage. The ICC may refer the case to its governing body or the UN Security Council for further action.

Italy's justice minister said on Wednesday Rome had no choice but to free a Libyan military officer wanted for war crimes by the International Criminal Court because of what he described as mistakes and inaccuracies in the court's arrest warrant.

Judges at the International Criminal Court have officially asked Italy on Monday to explain why the country released a Libyan man suspected of torture, murder and rape rather than sending him to The Hague.