ROME (Reuters) – Italy plans to transfer some migrants crammed aboard a charity boat onto other vessels on Tuesday and then sail them all to Spain, despite appeals from humanitarian groups to let the group land immediately.

The 629 migrants, including 11 children and seven pregnant women, have been drifting in the central Mediterranean aboard the Aquarius rescue ship since Sunday, when both Italy and Malta shut their ports to it.

Spain unexpectedly offered on Monday to take in the migrants, who were picked up off the Libyan coast over the weekend, but the Aquarius had still not moved more than 16 hours later as the authorities finalize logistics of the trip.

Italy’s coast guard said in a statement that two Italian ships would take on board some of the migrants, easing conditions on the overcrowded Aquarius. All three ships would then sail to the Spanish port of Valencia on a voyage expected to take four days.

Doctors Without Borders (MSF), which is operating the Aquarius alongside SOS Mediterranne, urged a rethink.

“This plan would mean already exhausted rescued people would endure 4 more days travel at sea,” it said on Twitter. “MSF calls for people’s safety to come before politics.”

It added: “The better option would be to disembark the rescued people in the nearest port after which they can be transferred to Spain or other safe countries for further care and legal processing.”

But Italy’s new anti-establishment government, looking to put pressure on the European Union to re-write its immigration rules, showed no signs of relenting despite warnings of an approaching storm bringing waves of over 2 meters (6.5 ft).

The Italian coast guard said it had contacted nations which are responsible for the waters the Aquarius convoy will cross to be on alert if there were any possible medical emergencies amongst the migrants that needed outside intervention.

MORE MIGRANTS AHEAD

Even as Italy worked to dispatch the charity ship, an Italian coast guard vessel with 937 migrants aboard was heading north from the Libyan coast and was expected to dock in Sicily on Wednesday.

“No one should dare brand Italy or its government as inhumane or xenophobic,” Transport Minister Danilo Toninelli told Radio Capital.

However, charities questioned why the coast guard boat was being allowed to dock in Italy, while migrants on the Aquarius, who had been at sea for longer, were not.

“Why do 629 people on Aquarius still have to suffer? NGOs do nothing differently to the coast guard,” the charity Sea Watch wrote on Twitter. “All a political stunt … at the expense of people in distress?”

Italy has taken in more than 640,000 mainly African migrants over the past five years. Efforts by Rome to persuade other EU states to accept some of the newcomers and share the cost of their care have largely fallen on deaf ears, heightening anti-European and anti-migrant sentiment in the Italy.

The far-right League scored its best-ever result in March national elections and has formed a coalition government with the anti-system 5-Star Movement.

League leader Matteo Salvini was sworn in as interior minister earlier this month and has vowed to clamp down on illegal immigration and change EU rules.

“To politely raise one’s voice pays off,” Salvini said on Monday. “It’s something Italy hasn’t done for many years.”