Italy “failed to respond promptly to various distress calls from the sinking boat, which was carrying more than 400 adults and children”, the committee of 18 independent experts found.
Rome “also failed to explain the delay in dispatching its navy ship, ITS Libra, which was located only about an hour away from the scene”.
The committee’s decision responds to a joint complaint lodged by three Syrians and a Palestine national, who survived the tragedy but lost their families.
On October 11, 2013, the boat had set out from the Libyan fishing port of Zuwarah, carrying mostly people who had fled from Syria.
The fishing vessel began taking on water after it was fired on by a boat flying a Berber flag when in international waters, 113 kilometres south of the Italian island of Lampedusa and 218 kilometres south of Malta.
Those on board made several calls to the Italian number for emergencies at sea, but were eventually told after 1:00 pm that they were in the Maltese search and rescue zone.
After desperate calls to the Maltese authorities, a Maltese patrol boat arrived at 5:50 pm.
The vessel had already capsized.
Malta urgently requested Italian help, and the ITS Libra navy ship, which was nearby, was finally instructed to go to the rescue after 6:00 pm.
As a result of the delayed action, more than 200 people, including 60 children, drowned.
“It is a complex case,” committee member Hélène Tigroudja said in a media release.
“The accident happened in the international waters within the Maltese search and rescue zone but the location was indeed closest to Italy and to one of its naval ships.
“Had the Italian authorities immediately directed its naval ship and coast guard boats after the distress calls, the rescue would have reached the vessel at the latest two hours before it sank.
“State parties are required under the international law of the sea to take steps to protect the lives of all individuals who find themselves in a situation of distress at sea.
“Even though the sinking vessel was not located in Italy’s search and rescue zone, the Italian authority had a duty to support the search and rescue mission to save the lives of the migrants.
“Italy’s delayed action had a direct impact on the loss of hundreds of lives.”
The committe called on Italian authorities to “proceed with an independent and timely investigation and to prosecute those responsible” for the deaths.
Italy and other countries involved in the tragedy also need to provide effective remedy to those who lost their families in the accident, the committee concluded.
Since 2014, more than 20,000 migrants and refugees have died at sea while trying to reach Europe from Africa.
While many have drowned at sea, thousands have been intercepted by the Libyan coastguard, which has been backed by Italy and the European Union, and returned to Libya.
They mostly end up in detention, often in horrific conditions.
Since February 2017, at least 36,000 people have been intercepted by the Libyan coastguard and returned to the North African country, UN figures show.
