The Aquarius, a rescue ship chartered by the French NGO, rescued 158 people, including nine children, 26 women and 36 unaccompanied minors, the organisation said in a statement. All were suffering from dehydration or showed signs of maltreatment, it added.
Salvini, who is also joint deputy prime minister in the populist coalition government sworn in on Friday, has ridden a wave of public discontent in recent years, playing on anti-immigrant sentiment as hundreds of thousands of migrants landed in Italy.
His far-right party surged in the polls ahead of a March election after he promised to deport hundreds of thousands of migrants and tackle what it calls the “danger” of Islam.
Asked about the arrival of Salvini on Sunday, Marco Rotunno of the UNHCR, the UN refugee agency, said it was too early to comment but added that “there are a lot of people fleeing war and persecution who are in need of international protection”.
Some 700,000 migrants have landed in Italy since 2013.
Salvini, who said he was making a trip to Sicily to assess the situation, has already pledged to cut funding for migrant reception centres to finance repatriation programmes for those living in Italy illegally.