Passengers include 11 children and seven pregnant women, as well as 123 unaccompanied minors.
He also complained, on Facebook that: "Malta takes in nobody". All passengers were offloaded to the Aquarius to be taken to land.
Salvini pointed to Malta's unwillingness in accusing Europe as a whole of leaving Italy on its own to deal with the refugee crisis. In practical terms, no ships of this type will be able to land without cooperation of the Italian coastguard, which is under the direct command of the Italian government.
On Sunday, Salvini said Italy was saying "no to human trafficking, no to the business of illegal immigration".
A French NGO's rescue ship, the Aquarius, was waiting for a port to dock at on Monday as a diplomatic standoff played out over where it should go next.More news: EU Will Act Against US Tariffs On Steel, Aluminum: Merkel
Italy has denied permission for a rescue ship to drop off 629 migrants after Malta refused to open its ports.
"This is not an inhumane act", said Transport Minister Danilo Toninelli, in charge of Italy's ports and coast guard. "The Mediterranean is the sea of all the countries that face it, and it (Malta) can't imagine that Italy will continue to face this giant phenomenon in solitude".
The migrants were saved by SOS Mediterranee on Saturday and are stuck aboard the French NGO's ship Aquarius, which is now between Malta and Sicily waiting for a secure port for her to dock. "RCC Malta in this case is neither the competent, nor the coordinating authority".
Maltese Premier Joseph Muscat also refused to take in the Aquarius ship of the humanitarian group SOS Mediterranee. The Rome-based rescue coordination center gave the instructions.
"If anyone thinks I won't move a muscle while we have another summer of landings, landings and more landings, well that's not what I'm going to do", Salvini told reporters.More news: The Elder Scrolls: Blades brings Bethesda’s fantasy series to iOS and Android
The group said it "urgently requests a swift resolution and a designated port of safety".
"Our only goal is to let the people we assisted yesterday in hard conditions to dock in a secure port".
The same day Italian authorities held the migrant rescue boat Sea-Watch 3 for 12 hours after it brought 232 people to Reggio Calabria, on the south-western tip of the mainland.
Salvini says Italy should not be the only country taking in boats arriving from North Africa and urges Malta to allow the ship to disembark.
One boat found Sunday was carrying four bodies along with 49 migrants. Right-wing politicians have accused charity boats operating off the coast of Libya of operating as "taxis" for migrants. The migrants were taken to a naval base in Tripoli.More news: Trump, Lee to hold bilateral meetings, working lunch today
Driven by violent conflicts and extreme poverty, hundreds of thousands of migrants have reached southern Europe in recent years by crossing the Mediterranean in smugglers' boats that often are unseaworthy.
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