A ship carrying more than 600 rescued migrants, including 123 unaccompanied minors and seven pregnant women, remained stranded in the Mediterranean Sea on Monday after Italy’s new populist government refused permission for it to dock the day before in a move described by rescuers as unprecedented.

Matteo Salvini, Italy’s hardline interior minister and leader of the anti-immigration League party, called on the country to “close the ports” and pledged Sunday to “STOP the filthy business of illegal immigration.”

The search-and-rescue ship Aquarius is operated by Doctors Without Borders (MSF) and the SOS Méditerranée organization. From Saturday night into Sunday morning, the Aquarius took on 629 people in six separate operations, MSF and SOS said on Twitter.

The boat has been stranded between Malta and the Italian island of Sicily since Sunday, when the Italian Maritime Rescue Coordination Center told Aquarius to hold its current position, according to MSF.

The ship is equipped for only around 550 people, according to Aloys Vimard, project coordinator on the Aquarius. Speaking to Spanish public radio broadcaster RNE Monday, Vimard said that on-board food supplies would last only one more day.

“MSF is concerned that again politics are being placed above people’s lives,” Vimard told CNN. “The priority must be the importance of the well-being and safety of the people on board.”

A number of passengers are in need of medical treatment, MSF tweeted, adding that 15 have serious chemical burns and several others have hypothermia. Dozens of people had spent almost a full day in the water by the time the Aquarius reached them, Laura Garel, communication officer with SOS Méditerranée France, told CNN on Monday.

None of those rescued are aware of the “ongoing diplomatic standoff,” MSF tweeted Monday, calling for “a swift resolution and a designated port of safety.”

In footage posted to Twitter by Euronews and NBC journalist Anelise Borges, women were sitting and lying on the floor in an enclosed area below deck, one fanning another to combat the heat. “It’s unbearably hot where they are,” Borges tweeted.

There are no showers or sinks for migrants on the Aquarius and rescue workers use a disinfectant spray on people’s hands before they eat. Drinking water supplies are unlimited as the ship has its own water purification system, but the passengers survive mostly on energy biscuits, prepackaged warm rice, tea and bread.

Women and children sleep below deck, watched over by a midwife, while the men sleep on the open deck, covered only with tarpaulin.

Nicola Stalla, search-and-rescue coordinator on the Aquarius, told CNN that the situation was unprecedented. “We have never been a situation before where we have been denied a right to a port of safety,” he said Monday via a WhatsApp message. “We are nonetheless prepared to take care of the rescued people until we are.”

More rescue ships on the way

Tensions in the Mediterranean are likely to rise as more rescue ships head for the Italian coast. According to Flavio di Giacomo, spokesman for the International Organization for Migration, an additional 790 migrants were rescued Sunday by the Italian Coast Guard.

“I don’t think the Italian government can deny a port of safety to the Italian Coast Guard, but they can to a foreign-flagged ship like the Aquarius,” he told CNN Monday. The Aquarius flies the flag of Gibraltar.

Also on Monday, Salvini signaled his intention to prevent a second foreign-flagged search-and-rescue vessel, Sea Watch 3, operated by a group of German volunteers and currently positioned off the coast of Libya, from docking.

“Italy has stopped bowing its head and obeying, this time THERE ARE THOSE WHO SAY NO,” he tweeted Monday.

“Everyone in Europe minds their own business, now Italy too is raising its head. STOP the filthy business of illegal immigration,” he tweeted Sunday. Salvini has also been using the hashtag #chiudiamoiporti, meaning “we close the ports.”

MSF said Sunday that Italy had reportedly asked Malta to allow the rescued migrants to disembark there. However, Malta’s Ministry for Home Affairs and National Security issued a statement saying the country is not responsible for the rescue effort coordinated by the Aquarius.

“Malta is in full conformity with international obligations & will not take the vessel in its ports. We will continue,where possible, carrying out individual&humanitarian emergency medical evacuations,” Prime Minister Joseph Muscat tweeted.

On Monday the UN Refugee Agency called for “concerned governments” to allow the immediate disembarkation of those on board the Aquarius, and to address the bigger political problems later.

“There is an urgent humanitarian imperative here,” said Vincent Cochetel, UNHCR’s Special Envoy for the Central Mediterranean, in a statement. “People are in distress, are running out of provisions and need help quickly. Broader issues such as who has responsibility and how these responsibilities can best be shared between states should be looked at later.”

‘A minister without heart’

In defiance of Salvini and the government’s anti-immigrant stance, several Italian mayors have suggested they would be prepared to welcome the Aquarius into their port.

Leoluca Orlando, mayor of the Sicilian capital Palermo, said his city “always will be ready to welcome ships, civilian or military, which are committed to rescuing lives in the Mediterranean” and accused Salvini of violating international law.

The mayors of Naples and Reggio Calabria — two coastal cities in mainland Italy — also said they would allow the ship to dock.

“If a minister without heart lets pregnant women, children, elderly, human beings die, the port of Naples is ready to welcome them. We are human, with a big heart,” said Luigi de Magistris, the mayor of Naples.

Such rhetoric is largely symbolic as the MRCC in Rome is the only organization that can authorize the docking of a foreign-flagged ship in Italy — city mayors do not have the power to do so. However, such strong and public rejection of the government’s immigration policy is likely put pressure on the new Prime Minister Giuseppe Conte, just a week into his first term.

Deadly crossing

Since 2015, when more than a million migrants and refugees arrived on Europe’s shores, governments across the continent have sought to fortify their countries’ borders.

The number of people attempting to cross the Mediterranean from northern Africa or Turkey has fallen sharply, largely as a result of two controversial deals: one struck in March 2016 between the European Union and Turkey — under which Syrian refugees arriving in Greece from Turkey are sent back — and another made last year between Italy and Libya, in which the southern European country pledged to bolster Libya’s coast guard so it could spot departing migrant boats and house migrants attempting to cross.

But with 3,116 deaths in 2017, the Mediterranean remained the deadliest migrant route in the world last year, according to the IOM. It said just under 70% of the 171,635 migrants who entered Europe by sea had arrived in Italy.

As of June 6, there had been an estimated 785 deaths on the route this year, the IOM said,with the majority of the 33,400 migrants and refugees arriving through Greece and Italy.

More than 100 migrants died in a single incident earlier this month when an overcrowded boat sank a few miles off the coast of Tunisia.