Sweden has suspended deportations of asylum seekers to Greece - the latest of several European countries to do so.
The decision by Sweden's Migration Board came as Greece faced a new influx of illegal migrants entering via its land border with Turkey.
Last week, Austria stopped sending asylum seekers back to Greece and earlier Norway and Finland did so too.
Most illegal migrants trying to enter the EU arrive first in Greece, whose treatment of them has been criticised.
Under the EU's Dublin II Regulation, asylum seekers generally have to be processed by the first EU member state they come to. That means many have been sent back to Greece.
But in Greece far fewer asylum seekers are granted refugee status than in northern European countries.
Sweden's decision affects about 100 people who would otherwise have been returned to Greece, said Swedish Migration Board director Dan Eliasson.
"The situation in Greece is deteriorating constantly for asylum seekers," the AFP news agency quoted him as saying.
Last month a UN special rapporteur, Manfred Nowak, said Greek holding centres for migrants were in a "critical state" and conditions for many of them were "inhuman".
Greece says its border officials and police are struggling to cope with a surge in border crossings by illegal migrants. On Tuesday a special EU border team began deploying near the border with Turkey to help the Greek authorities.
Mr Nowak said Greece's backlog of unprocessed asylum claims totalled 52,000 in August.
In the second quarter of this year 90% of the migrants detected trying to enter the EU illegally were on the Greek land border, the EU border agency Frontex says.