Nearly 400 refugees and migrants remained stranded in the central Mediterranean after an overcrowded rescue vessel was emptied of all the rescued people on Saturday.
The German-flagged Louise Michel, sponsored by British street artist Banksy, made a mayday call late on Friday after rescuing more than 200 people, saying the 31-metre (101-foot) ship had become overcrowded and unable to move, reports Al Jazeera.
The crew said some of the survivors had fuel burns and had been at sea for days, and one of the boats the Louise Michel helped had at least one dead person on board. The survivors later said three people had died at sea before the arrival of the Louise Michel.
Over the course of Saturday, 49 survivors were picked up from the Louise Michel by the Italian coastguard and taken to the island of Lampedusa.
"Given the danger of the situation, the coastguard sent a patrol boat to Lampedusa which took in 49 people deemed the most fragile, including 32 women, 13 children and four men," the coastguard said in a statement.
The remaining survivors were transferred on Saturday to another charity vessel, the German-flagged Sea-Watch 4, jointly operated by the NGOs Sea Watch and Doctors Without Borders (MSF).
"LouiseMichel no longer has guests onboard, but the struggle of the survivors is not over," a Twitter account for the rescue ship said on Sunday. "Europe! SOLAS [international treaty on safety of life at sea] obliges you to rescue at sea. Open your ports now!"
The Sea-Watch 4, which has a clinic on board and is itself in search of a host port, sailed for almost 12 hours to help the Louise Michel.
The Sea-Watch 4 now has 353 rescued people, while another 27 are still on the Maersk Etienne, a Danish tanker that rescued them on August 4 after a call for assistance from the small boat they were on.
"We're providing an emergency response where the states are failing and now we're stranded at sea. We are being penalised for filing the gap that the EU governments have left at the world's deadliest maritime border," Hannah Wallace Bowman, MSF's field communications manager on board the Sea-Watch 4, said.
"The crew and survivors on board the Sea-Watch 4 are totally exhausted. Some of the people who we rescued have been on board since last Saturday, more than seven days ago."
'Immediate disembarkation'
The UN refugee agency (UNHCR) and the International Organisation for Migration (IOM) jointly called for the "immediate disembarkation" of all survivors still at sea.
EU countries' inability to agree who should take them in "is not an excuse to deny vulnerable people a port of safety and the assistance they need, as required under international law," they said.
The Mediterranean route is described by the UNHCR as the most dangerous migration route in the world - one in six people who depart the shores of North Africa dies.
Since 2014, more than 20,000 refugees and migrants have died at sea while trying to reach Europe from Africa, fleeing conflict, repression and poverty in Africa and the Middle East.
The reality is far worse than what the figure suggests officials and analysts have warned, as the bodies of those who do not survive are not always recovered, identified and counted.
Standoffs over refugees and migrants rescued in the central Mediterranean have been playing out for years, with the southern European counties of Italy and Malta usually reluctant to welcome them.
The two countries have long said they are disproportionately affected by Europe-bound sea migration from North Africa, and that there is insufficient burden-sharing across the European Union.