The European Union and the United Nations refugee agency called for a swift end to a political standoff that has left 629 migrants on a rescue ship drifting at sea on Monday after Italy and Malta refused to let it dock.
The Aquarius ship picked up the migrants, including 123 unaccompanied minors, 11 other children and seven pregnant women, from inflatable boats off the coast of Libya at the weekend.
It sailed north towards Italy, but Matteo Salvini, the head of the far-right League party who became interior minister this month vowing to crack down on the influx of migrants from Africa, blocked the ship and said it should go to Malta instead.
Malta refused, saying it had nothing to do with the rescue mission, which was overseen by Italian coastguard. The island nation with fewer than a half a million inhabitants says it already accepts more refugees per capita than Italy, which has taken in more than 600,000 boat migrants since 2014.
"Saving lives at sea is a duty, but transforming Italy into an enormous refugee camp is not," Salvini said on Facebook on Monday. "Italy is done bowing its head and obeying. This time there's someone saying no."
Pictures from aboard the Aquarius, which is operated by SOS Mediterranee and Doctors without Borders, showed hundreds of Africans huddled aboard, including a young girl wrapped in a blanket in the arms of a rescue worker.
"People are in distress, are running out of provisions and need help quickly," the UN refugee agency said, urging governments to set aside political considerations.
"Broader issues such as who has responsibility and how these responsibilities can best be shared between states should be looked at later," UNHCR special envoy Vincent Cochetel said.
SOS Mediterranee said the Gibraltar-registered ship had enough supplies to feed the migrants, at least for another day.
EU law requires asylum seekers register in the first safe country they reach, but frontline countries such as Italy and Malta say the burden needs to be shared out across the bloc.
"This is not an inhumane act," said Transport Minister Danilo Toninelli, in charge of Italy's ports and coast guard.
"It's common sense ... We ask that all of Europe assume responsibility for such a delicate and important issue as is immigration," he said in a TV interview.
Not everyone in Italy agreed with the government action, and the mayors of a number of southern cities, including Naples, Palermo and Messina, said they would welcome the migrants.
Palermo Mayor Leoluca Orlando said Salvini was "violating international law which makes saving lives a priority".
The European Commission urged action.
"We are talking about people ... The priority of both the Italian and Maltese authorities should be ensuring these people receive the care they need," Commission spokesman Margaritis Schinas told a news conference.
"We call on all involved to contribute to a swift resolution so that the people on board the Aquarius vessel may be safely disembarked as soon as possible."
Maltese Prime Minister Joseph Muscat said on Sunday that he had told his Italian counterpart, Giuseppe Conte, his country would not take the ship.
"We are concerned at Italy authorities' directions given to Aquarius on high seas. They manifestly go against international rules, and risk creating a dangerous situation for all those involved," Muscat said on Twitter.
By law, it will be difficult for Italy to refuse the boat a safe haven, as its own Coast Guard coordinated the rescues, picking up more than 280 migrants in its own vessels before transferring them to the Aquarius to be taken to safety.
Salvini doubled down on his position, warning another rescue ship, that is registered in the Netherlands and operated by a German charity, that it may not be allowed to dock in Italy if it picks up migrants off Libya, where it is currently sailing.
"Malta is not acting, France rejects them, and Europe doesn't care," Salvini wrote. "I've had enough."
The Sea Watch still did not have any migrants on board, spokesman Ruben Neugebauer said. While he agreed that there should be a more fair distribution of migrants in the EU, he said Salvini was "making a point at the cost of people in distress ... It's highly irresponsible."