Italy on Monday denied safe harbour to the 141 people rescued by the humanitarian ship Aquarius off the coast of Libya last week, setting up another stand-off with European Union allies over who would take them in.
The Aquarius, run by Franco-German charity SOS Mediterranee and Doctors without Borders (MSF), picked up the people in two separate operations and is now in international waters between Italy and Malta.
Malta said it had no legal obligation to berth the ship while Spain said its ports were not the safest destination for the vessel.
More than 650,000 migrants have come to Italy's shores since 2014, prompting Rome to accuse its EU peers of not sharing the burden of caring for those who arrive on the bloc's southern border.
The Aquarius spent nine days at sea in June after Italy's new populist government took office and shut its ports to all humanitarian boats, calling them a "taxi service" and accusing them of helping people smugglers — charges the charities deny.
"It can go where it wants, not in Italy!" far-right Interior Minister Matteo Salvini said of the Aquarius on Twitter on Monday, mentioning France, Germany, Britain or Malta as destinations.
"Stop human traffickers and their accomplices," he wrote.
Transport Minister Danilo Toninelli, who oversees ports and the coast guard, said the ship's flag country, which is Gibraltar, should take responsibility.
"At this point, the United Kingdom should assume its responsibility to safeguard the castaways," Toninelli said on Twitter.
The British foreign office was not immediately available for comment.
The European Commission was in touch with several EU states and trying to help resolve the "incident" with the Aquarius, a spokesman in Brussels said. She added that while Britain could theoretically be considered as a destination port, it was not practically feasible to bring the ship there.
Malta rejected any suggestion the Aquarius should dock in its ports, saying the latest rescue was made closer to Libya, Tunisia and Italy than to its own shores.
"Malta was neither the coordinating nor the competent authority ... and therefore has no legal obligation to make the arrangements to provide for a place of safety. The requests for the vessel to enter our ports are unwarranted and without legal standing," it said in a statement.
Earlier on Monday, Malta's armed forces rescued 114 migrants from a rubber dinghy taking on water 53 nautical miles south of Malta and brought them back to the Mediterranean island.
In June, the Aquarius ended up taking some 630 migrants to Spain, which welcomed it. But on Monday, Madrid did not repeat its offer, with a government spokeswoman saying: "At the moment, Spain is not the safest port because it is not the nearest one" for Aquarius to dock.
The Aquarius' search and rescue coordinator Nick Romaniuk said some migrants on board were sick and wounded and "need to be disembarked as soon as possible" for proper medical care.
Due to pressure from Italy and Malta, most charity ships are no longer patrolling off the coast of Libya.
Though departures from Libya have fallen dramatically this year, people smugglers are still pushing some boats out to sea and an estimated 720 people died in June and July when charity ships were mainly absent, Amnesty International estimates.
Protracted feuds between EU states over how to handle immigrants have thrown the issue back onto the European agenda. That is despite overall Mediterranean arrivals having dropped sharply since the 2015 peak when a million people arrived.
EU border agency Frontex said on Monday it counted 73,500 "irregular border crossings" into the bloc so far this year via the sea and the Western Balkans route, more than 40 percent fewer than in the first seven months of 2017.