Police in Cagliari on Tuesday said they arrested an Algerian who had re-entered Italy aboard a people smuggling boat after being deported.
The Algerian was among 66 migrants who landed overnight on Saturday on the southwest Sardinian island of Sant'Antioco.
According to the interior ministry's database, the man previously arrived in Sardinia in January 2016, police said.
Hardline interior minister Matteo Salvini has vowed to deport half a million illegal immigrants and to achieve "zero" migration to Italy.