Some of the 49 migrants stranded off the coast of Malta are refusing food, one of the groups running the boats that rescued them reported Monday.
"On board of #SeaWatch we are reporting episodes of people refusing food," Sea-Watch International tweeted Monday.
"We fear that their psychological and health status may deteriorate significantly," it added.
The migrants, rescued while attempting the dangerous Mediterranean crossing from north Africa to Europe, have been stranded on the Sea-Watch and another boat since December 22 since no country has allowed it to dock.
But the diplomatic deadlock among EU member states has still not been resolved, despite Pope Francis's appeal on Sunday for EU leaders to show solidarity towards the migrants.
The Sea-Watch and the Sea-Eye, who between them have 49 migrants on board, including a baby and a number of children, remain off the coast of Malta.
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On Sunday, Sea Watch spokeswoman Giorgia Linardi described how the migrants, crammed into a small room, were vomiting on each other in the stormy seas.
One European diplomatic source said France, Germany, Luxembourg, Malta, the Netherlands and Portugal had declared themselves ready to take in some of the migrants.
So too has Romania, which currently holds the six-month rotating EU presidency, agreeing to take in five migrants.
But both Italy and Malta have repeatedly refused port access to the rescue vessels and they stuck to that position Sunday despite the pope's intervention.
Italy's far-right Interior Minister Matteo Salvini maintained his position on Monday.
"I don't understand why ... if there are 49 people in Maltese waters on German and Dutch boats, it's still the problem of the Italians," he told journalists.
Relations between Italy and Malta have been strained since Salvini's decision to close Italian ports to the migrants, accusing the groups who rescue them of running a migrant "taxi service".
Frank Doerner, a doctor on board the Sea Watch, said on Sunday: "The situation here on board is getting more and more unstable." And because they were unable to land the migrants they had rescued, that prevented them from going back out to sea to rescue others risking the crossing.