Italian navy says at least 40 dead while hundreds of people were rescued, as it continues operation to save more.
Clashes have broken out between migrants on the Greek island of Kos amid complaints that some nationalities have been getting preferential treatment in processing, as migrants continue to struggle to get food and water.
Dozens of migrants from Pakistan, Afghanistan and Iran threw stones and exchanged blows outside the island’s police station as they waited to get the papers required for them to leave Kos for the mainland, however they found the station was closed on a Greek public holiday.
Al Jazeera’s Emma Hayward said that it was unclear who started Saturday’s clashes but “there was no holding back”.
“Anger, frustration and suspicion boiled over under the intensity of the summer sun,” she said.
An Iranian migrant told Al Jazeera that : “Afghanistan, Pakistan, your ticket [and] go. Just Irani, relax, sit down, sit down. What relax? Please no. Just Iran no ticket, no paper. What happened? Please can you help?”
Overwhelmed, the Greek government sent a passenger ferry to act as a temporary registration centre off the island and the vessel took hundreds of migrants to Athens on Friday.
Another boat was preparing to take a load of Syrian migrants to the mainland but was yet to start operating. Under international law, people fleeing war have greater rights than economic migrants.
The authorities said migrants of all nationalities would be processed.
A migrant camp on the island, run by Medecin Sans Frontieres (MSF) at the Captain Elias Hotel, provides basic facilities like mattresses and portable toilets but the organisation told the Reuters news agency they were struggling to cope with the number of arrivals.
Migrants, without food and water, have also been sheltering from the intense heat in tents and cardboard boxes.
Kos, within sight of Turkish shores, has found itself on the frontline of the crisis as new migrants arrive in rubber dinghies at the rate of hundreds a day.
Nearly a quarter of a million migrants have crossed the Mediterranean to Europe this year, according to the International Organisation for Migration.
Of these, about half have come to the Greek islands, with numbers surging in the summer when calmer weather makes the crossing less risky.
“Greece was not prepared for this and Athens has called for help from the outside world,” our correspondent said.
“It is though, still waiting.”