Austrian Chancellor Werner Faymann vowed early Friday to proceed with plans to limit the number of asylum requests his country will accept this year, despite EU pressure to postpone the controversial and potentially illegal measure.
"We said that we will take 37,500" asylum applications for this year, he told journalists after talks with his EU counterparts at a summit in Brussels. "That is the political decision and it has to be implemented in accordance with the law."
"There is nothing to delay, there is nothing to change," he added.
Vienna had set the limit in January, a fraction of last year's 90,000. On Wednesday, Interior Minister Johanna Mikl-Leitner announced that the entry of refugees at the border would thus be limited to 3,200 per day for people transiting to other European countries, and to 80 for those who seek asylum in Austria.
But fears are rife that the move will set off a domino effect, leading Western Balkan nations to also clamp down on the movement of asylum seekers and creating a humanitarian crisis in Greece, where most refugees currently arrive from Turkey before moving on north.
"We must remain united and show solidarity, but united and with solidarity everywhere, not only in the north-western side of Europe," Greek Prime Minister Alexis Tsipras told journalists in Brussels.
Balkan countries are already following Austria's cue with plans to stop migrants at their borders.
Slovenia is in the process of giving the army authority to police borders, while Macedonia began reinforcing and expanding a mesh and razor-wire fence on the path of migrants arriving from Greece.
In Belgrade, the minister in charge of migration, Aleksandar Vulin, said: "Serbia will do as Austria does."
The police chiefs of Austria, Slovenia, Croatia, Serbia and Macedonia, meanwhile, signed an agreement in Zagreb with immediate effect to screen migrants at the Macedonian border and transport them on to Austria and Germany, Croatian state TV HRT reported.
This came despite a summit call by the EU leaders for an "end to the wave-through approach" along the Western Balkan migration route.
Several leaders demanded that Austria postpone the introduction of its quota until their next regular meeting on March 17-18, sources said on condition of anonymity.
Belgian Prime Minister Charles Michel said the talks were tense, with a division "between those who believe we can find solutions together and those who prefer to act alone."
Just hours earlier, the European Union's top migration official had upped the pressure by writing to Vienna that its daily and annual limits for asylum seekers were unlawful.
"Such a policy would be plainly incompatible with Austria's obligations under European and international law," EU Migration Commissioner Dimitris Avramopoulos wrote to Mikl-Leitner, in a letter obtained by dpa.
"Austria has a legal obligation to accept any asylum application that is made on its territory or at its border," he added.
But Mikl-Leitner defended her policies by pointing to similar daily quotas by neighbouring Germany, which had resulted in up to 18,000 migrants being stranded temporarily in Austria last year.
She also told dpa that her country's tighter border policies were needed to keep nationalist sentiments at bay in Europe.
"These measures are not against Europe, but for Europe," said the minister, who is under pressure from growing support for the anti-foreigner Freedom Party.
The EU had put much of its hope in the migration crisis on Turkey, but has had limited success so far in getting the country to hold back migrants.
The leaders called early Friday in a joint statement for "further, decisive efforts" from Ankara and "a substantial and sustainable reduction of the number of illegal entries from Turkey into the EU."
If this does not materialize, "the talks about closing the borders of central Europe and securing the borders of the Western Balkans will become a new reality," Czech Prime Minister Bohuslav Sobotka warned.
The EU is now planning a summit with Turkey in early March to discuss the migration crisis, German Chancellor Angela Merkel said.
"I am very satisfied with the [EU summit] discussion," she added.
The leaders agreed that a deal struck with Turkey to stem migrant flows - in exchange for financial aid and closer political ties - "remains a priority and we must do all we can to succeed," EU President Donald Tusk said.
"We have confirmed that there is no alternative to a good, intelligent and wise cooperation with Turkey," European Commission President Jean-Claude Juncker added.