The UN has described conditions on Greek islands where thousands of refugees have landed as "total chaos," calling on Athens to take control. But the Greek prime minister says his country cannot cope alone.
Speaking on Friday after visiting several Greek islands, the UN refugee agency's Europe director, Vincent Cochetel, called conditions there "totally inadequate," noting deficiencies in water supplies, sanitation and food assistance.
"On most of the islands, there is no reception capacity; people are not sleeping under any form of roof," Cochetel told reporters.
"It's total chaos on the islands. After a couple of days they are transferred to Athens; there is nothing waiting for them in Athens," he said, adding that he had "never seen a situation like that."
He called on Greek authorities to "lead and coordinate the response."
"We are concerned with the situation where no one is really assuming leadership in the response, which makes it very difficult for humanitarian operators to participate in the efforts," said Cochetel, who has worked with the UN High Commissioner for Refugees for 30 years.
This was an appeal echoed by Greek Prime Minister Alexis Tsipras on Friday, who said his country could not cope alone with the migrant influx.
"Now is the time to see if the EU is the EU of solidarity or an EU that has everyone trying to protect their borders," Tsipras said.
"The immigrant flow to Greece is beyond what our state infrastructure can handle," he said, speaking after a meeting with ministers about the migrant crisis.
Greece's economy is falling into recession again after briefly appearing to stage a recovery from six years of depression caused by its rampant debt crisis. It is currently negotiating with the EU and the International Monetary Fund for a third bailout to stave off financial collapse
Turning to the crisis in Calais, France, where thousands of migrants are camping out in makeshift settlements in the hope of crossing the English Channel to Britain, Cochetel said the government needed to draw up an emergency plan to provide dignified accommodation.
"Let's treat that as a civil emergency," Cochetel said.
The refugee camps in Calais also lack adequate water and sanitary facilities, but are currently tolerated by the French authorities.
At least 10 people have died trying to reach Britain through the Channel Tunnel, some after jumping on to the train that uses the tunnel to carry vehicles to England.