Deep-seated Balkan tensions inflamed by the migration crisis were laid bare on Sunday as regional leaders attempted to “avoid a humanitarian tragedy” and persuaded Greece to house 50,000 asylum seekers.

The hastily arranged Brussels summit of 11 countries, convened by the European Commission, attempted to ease friction and bring order to a western Balkans migration route where overwhelmed governments are increasingly turning on each other.

Jean-Claude Juncker, the commission president, sought to cut through gnarled regional politics with a joint pledge from leaders to enforce rules on registration, rush border guards to pinch-points and pressure Greece into accepting more help.

After persistent demands from Berlin and Brussels, Athens agreed to set up 30,000 holding places for asylum seekers by the end of the year — an idea it had previously resisted — with “financial help” from other member states. Another 20,000 places would be provided in conjunction with the UN refugee agency UNHCR, with asylum seekers even being hosted by Greek families.

Leaders pledged to create 100,000 places in total, with an additional 50,000 spots established elsewhere along the western Balkans route, which stretches from Greece, through former Yugoslavia up to Austria and Germany.

The diplomatic push is part of the frantic efforts by German chancellor Angela Merkel — who initially wanted to convene the meeting in Berlin — to bring a semblance of control to the human chain winding through south-eastern Europe to Germany just as winter approaches. “Extraordinary times demand extraordinary measures,” she said.

Miro Cerar, Slovenia’s premier, whose country of 2m has received 60,000 refugees in 10 days, said if concrete action was not taken within days “the EU will start falling apart”.

“There is some fear in the air that Germany and consequently Austria will close their borders, which will lead to a domino effect that will be disastrous for Europe," said Mr Cerar. "This is something that we should all be aware of.”

Mr Cerar warned that unless the commitments were implemented swiftly the entire EU system would be endangered. While making no mention of Slovenia potentially building a border fence, he said without concrete support he would be left no option but to take “additional measures” as Ljubljana struggles to cope with the influx.

In the small Slovenian town of Brezice, hundreds of refugees were huddled in an overcrowded camp on the banks of the Sava River about a dozen kilometres from the Croatian border.

Many were sleeping outdoors in the mud, surrounded by litter, with little or no access to food, water or medical assistance. Aid workers said many migrants were suffering from hypothermia, as temperatures dropped as low as 7C at night.

“We’re suffering here,” said Suhela Sahaddoun, a 33-year-old Syrian who was travelling with her two daughters, aged 4 and 11, and her son, aged 13. Nearby, behind a fence, Amina Al-Hussein pleaded for milk or baby formula for her one-year-old son Aslan. Her neighbour complained that conditions were worse in Brezice than at any other point along their journey from Syria.

With communication between Balkan countries poor at the best of times, many of the leaders took the opportunity to blame neighbours for the crisis on their borders, with Greece coming in for particular fire.

The most contentious measure raised at the summit involved dramatically increasing Greece’s capacity to hold and process refugees, through a combination of Athens-controlled reception centres and other measures, such as housing asylum seekers in Greek family homes.

Greece’s creaking asylum system has been repeatedly condemned by the European Court of Human Rights for its “degrading” conditions. UNHCR will be involved partly to assuage concerns over Greece’s chequered record when it comes to handling asylum claims, according to EU officials.

While migration experts welcomed the extra places, many suggested that it was still not enough. About 48,000 people arrived in Greece in just five days last week as bad weather and rough seas did little to stop people making the trip.

Under the scheme, those held in the reception centres across Greece would be processed, before being shared out under an EU scheme to relocate 160,000 asylum seekers across other countries in the EU.

But a lack of relocation places means that Greece risks becoming a bottleneck, with other national capitals having so far put up only 854 of the proposed 160,000 spots.

Alexis Tsipras, Greece’s prime minister, blamed the crisis in Europe on a “not in my backyard” approach and called on leaders to focus on Turkey for a solution. “The problem is not the hotspots,” he said, referring to Greece’s limited reception capacity. “The problem is the routes.”

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