“The Sea-Watch 3 is free! We have received formal notification of the ship's release from confiscation and its subsequent return to operations,” Sea Watch said on Twitter.
The Dutch-flagged vessel was impounded on May 20 after rescuing migrants off Libya and bringing them to Italy, where interior minister Matteo Salvini of the far-right League had warned the ports were closed.
The migrants were allowed to disembark on Italy's Lampedusa island, starting with the 18 most vulnerable — children and people needing medical care — then the remaining 47.
The rescue infuriated Salvini, whose popularity has soared thanks largely to his hardline migration policy.
The League head, who has attributed a decline in the number of deaths at sea to a deal made with the Libyan coastguard to prevent people from heading to European shores, has repeatedly insisted Italy's ports are closed to migrants.
Salvini says those setting sail from Libya to seek safety in Europe should be returned to the crisis-hit country — an order that is illegal under international law, and which charity-run migrant rescue vessels have repeatedly refused to follow.
An Italian military ship which rescued 100 people Thursday, saying their lives had been in imminent danger after their boat's engine failed in worsening weather, was expected to bring them to the port of Genoa Sunday.
Salvini said Saturday he had clinched an agreement with five European countries and the Vatican to host those saved, having earlier said he was determined “not a single immigrant” would be paid for by the Italian taxpayer.
“A part of the immigrants will be taken in by five other European countries, while all the others will be given hospitality by the Vatican,” he said, without naming the countries. There was no immediate confirmation from the Vatican.