The migrant rescue ship Aquarius has sailed back to international waters off Libya, the EU Observer reports, and Salvini has said that it will not be allowed to dock in Italy.
The ship is there to resume work, despite the past issues with Italy and Malta and the recent disputes as to which of the two countries should take migrants picked up at sea.
The Aquarius is run by French charities SOS Mediterranee and Medicins sans Frontieres.
The EU Observer states that no charity ships have worked in the region since August when Italy refused to let people from the Aquarius disembark.
Italian Interior Minister Matteo Salvini has since warned that the ship will not be allowed to dock in Italian ports.
The Aquarius was last in Malta on 15 August, when all 141 immigrants who arrived in Malta aboard disembarked after an ad-hoc agreement was reached with a number of EU nations to relocate them.