The migrants, most of whom are believed to be from Eritrea, were given permission to come ashore early on Sunday after a five-day standoff between the Italian government and the EU, UN refugee agency and aid organizations.
As the rest of the group headed to a shelter, on Sunday evening Italian police detained three Egyptians and one Bangladeshi national suspected of helping to organize the boat crossing that left around 200 people in the waters between Malta and Sicily, where they were rescued by the Diciotti some 11 days ago.
According to Ansa news agency, the four are accused of criminal association for the purposes of human trafficking, aiding illegal immigration, illegal entry by procurement, and sexual violence.
The other people rescued were taken to a former military barracks in the Sicilian city of Messina, where they will wait to be processed and informed where they are going next.
Under a deal brokered by the Catholic Church, Catholic authorities in Italy will take responsibility for 100 of the migrants, with the remaining 40 or so distributed between Ireland and Albania.
Photo: Giovanni Isolino/AFP
According to Pope Francis, the Church will receive the group at its Mondo Migliore ('Better World') reception centre in Rocca di Papa, south of Rome, where they will "start to learn the language and become integrated migrants".
Italy's interior minister, Matteo Salvini of the anti-immigration League party, initially refused to allow the Diciotti to disembark when it arrived at the port of Catania last Monday, insisting that all those aboard were illegal immigrants and had no right to apply for asylum.
Of the 177 people the ship arrived with, some 30 unaccompanied minors were allowed to disembark midweek, followed by a dozen adults said to be in need of medical attention. Several of those aboard say they suffered torture, rape and other abuses in Libya prior to making the crossing, according to doctors allowed to examine them.
After the Italian government threatened to halt its contributions to the EU unless other countries offered to host the rescued migrants, the Catholic Church intervened and finalized a deal on Saturday night.
Meanwhile prosecutors in Sicily said they had opened an inquiry into Salvini for "illegal confinement, illegal arrest and abuse of power" over the interior minister's refusal to allow the rescued people ashore.