Migrants sit aboard MV Aquarius, a rescue vessel, at the Mediterranean sea between Libya and Italy | Louisa Gouliamaki/AFP via Getty Images Italian mayors rebel against Salvini’s order to block migrant ship Italy’s new interior minister has refused to let 600 migrants disembark in Italy, leaving a rescue ship in limbo in Mediterranean.

A number of mayors across southern Italy are pushing back against Matteo Salvini's decision Sunday to close off the country's ports to a rescue ship carrying more than 600 migrants.

Salvini — Italy's new interior minister and leader of the far-right League — on Sunday refused to grant the vessel permission to dock in Italian ports and called on the island of Malta to take in the boat's 629 passengers. The Maltese government refused the request, stating international law required the passengers be unloaded in Italy.

Naples is "ready, without funds, to save human lives," the mayor of Naples tweeted, calling Salvini a "heartless minister."

The mayors of Palermo, Taranto, Messina and Reggio Calabria, have also said they would be ready to welcome the vessel.

"We have always welcomed rescue boats and vessels who saved lives at sea. We will not stop now," Leoluca Orlando, the mayor of Palermo, said. “Salvini is violating the international law. He has once again shown that we are under an extreme far-right government.’’

The League leader defended his decision in a Facebook post, writing: "Malta takes in nobody. France pushes people back at the border, Spain defends its frontier with weapons. From today, Italy will also start to say no to human trafficking, no to the business of illegal immigration.”

The decision ultimately rests with Salvini's government because a ship typically cannot dock without the presence of the Italian coast guard, which is controlled by Rome.

The migrants onboard the ship were picked up in six rescue operations that also involved Italian naval units, according to SOS Mediterranée. Passengers include 11 children and seven pregnant women, as well as 123 unaccompanied minors.

The vessel is now awaiting "definitive instructions," the humanitarian group said.