The refugee crisis on three Greek islands near Turkey is “total chaos”, the UN refugee agency UNHCR says.
Accommodation, water and sanitation are all inadequate for the many asylum seekers on Kos, Chios and Lesbos, the UNHCR says, calling it “shameful”.
Greek PM Alexis Tsipras said the problem “surpasses” Greece’s abilities and asked for EU help.
The UNHCR says nearly all new arrivals in Greece are refugees from the wars in Syria, Iraq and Afghanistan.
The organisation’s European Director, Vincent Cochetel, said facilities for the refugees on the Greek islands were “totally inadequate”, after a 750% increase in migrants arriving this year, compared with the same period last year.
He said 124,000 had arrived in Greece so far in 2015, including 50,000 in July alone.
Greece’s EU partners must do more to ease the burden, he said, but Greece must “lead and co-ordinate”.
“On most of the islands there is no reception capacity, people are not sleeping under any form of roof. So 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 complained.
Mr Tsipras said Greece’s economic crisis meant it was facing a humanitarian “crisis within a crisis”.
In Austria, the authorities have stopped taking in any more migrants at the country’s main reception camp, 20km (12 miles) south of Vienna.
Another UNHCR official described conditions at Traiskirchen as “intolerable, dangerous and inhumane”.
About 4,500 people are at the camp, which was built to house 1,800. Many are now sleeping in the open.
Most arrived in Austria via neighbouring Hungary – both EU member states and both in the border-free Schengen zone, where passports are generally not checked.
A deadly week
Meanwhile the EU is struggling to cope with the thousands of migrants heading for Italy aboard unseaworthy vessels from Libya, where people traffickers are charging huge sums to smuggle them into Europe.
As many as 200 migrants are feared drowned after a boat reportedly carrying up to 600 people – mostly Syrians – sank off Libya this week.
An Irish navy ship, LÉ Niamh, docked in Sicily on Thursday with 367 migrants who were rescued. The warship also brought 25 victims in coffins.
The EU border agency Frontex also says it has not received enough pledges of assets from EU states to help Greece and Hungary with the current influx of migrants.
Hungary is constructing a border fence, after a surge in migrants travelling up through Serbia from Greece.