Further chaos loomed as a French court approved the partial evacuation of the "Jungle" migrant camp near the port of Calais on the coast, a move that Belgium fears will send Britain-bound migrants coming its way.
Attempts by EU interior ministers meeting in Brussels to agree a unified response to the biggest migration crisis in the bloc's history frayed over the fact that many states are increasingly taking matters into their own hands.
The talks descended into acrimony over Austria's decision to freeze Greece out of a meeting earlier this week with Balkan states, at which they agreed steps that would effectively trap many asylum seekers on Greek territory.
Debt-stricken Greece -- the main landing point for most migrants arriving in Europe from Syria, Iraq, Afghanistan and other countries -- faces huge pressure to stop "waving through" migrants to the rest of the EU.
The Greek foreign ministry hit out at what it called "19th-century" attitudes and said it was recalling its envoy from Vienna to "safeguard friendly relations between the states and peoples of Greece and Austria".
'Warehouse of souls'
Greek Migration Minister Yannis Mouzalas meanwhile said his country "will not accept becoming Europe's Lebanon, a warehouse of souls" -- referring to the huge number of Syrian refugees Lebanon has taken since 2011.
The migration crisis shows no signs of abating with 100,000 arriving in Europe so far this year on top of one million in 2015, with most of them coming via Turkey across the Aegean Sea to the Greek islands.
EU migration commissioner Dimitris Avramopoulos said the bloc's migration system could crumble if the number of migrants does not fall by the time EU leaders hold a crucial summit with Turkey in Brussels on March 7.
Europe's passport-free Schengen zone has been cracking under the pressure of several countries reintroducing border controls, while the EU system stipulating that refugees must claim asylum in their country of arrival is increasingly ignored.
"In the next 10 days, we need tangible and clear results on the ground. Otherwise there is a risk that the whole system will completely break down," Avramopoulos said.
"The possibility of a humanitarian crisis is very real and very near."
Avramopoulos urged EU states to avoid "unilateral actions", such as recent caps on asylum seeker numbers brought in by Austria, which have left thousands of refugees stranded between member states.
But Austria and the Balkan states insist they need to act because the EU's plans are not working and Greece is not doing enough.
"If it is really the case that the Greek external border cannot be protected, can it be still a Schengen external border?" Austrian Interior Minister Johanna Mikl-Leitner said.
Calais 'jungle' part-closed
In France, a court gave the green light to plans to evacuate hundreds of migrants from the notorious "Jungle" camp in Calais, a process the mayor said would take place over the next three weeks.
Many migrants want to stay near the entrance to the Channel Tunnel, the gateway to their ultimate goal of Britain, and Calais town authorities said that no-one will be evacuated from the "Jungle" by force.
Belgium has decided to impose checks at the border with France to stop people coming from the Calais camp, a decision that French Interior Minister Bernard Cazeneuve on Thursday branded "strange".
Meanwhile in northern Greece, hundreds of migrants and refugees left an accommodation camp to walk to the distant border with Macedonia, days after Skopje slashed the number of people it allows through each day.
"They are mainly youths... they do not want to wait for buses to pick them up... neither the army nor the police can stop them because there is the risk of (violence)," Thessaloniki Mayor Yiannis Boutaris said.
The European Commission said separately it failed to "understand" Hungary's decision to hold a referendum on mandatory quotas for refugees that the bloc agreed last year.
So far only 598 people have been relocated from frontline states Greece and Italy, out of a planned 160,000.
In a positive development, NATO on Thursday managed to overcome sharp differences between long-time rivals Greece and Turkey to finalise an unprecedented naval mission to tackle migrant smugglers in the Aegean.