Balkan countries are threatening to close their borders if European Union members in northern Europe stop accepting asylum seekers streaming north from Greece and Macedonia.

Bulgaria, Romania and Serbia warned they would not allow themselves to become a “buffer zone” for the tens of thousands of arrivals streaming into Europe.

“All three countries … are ready. If Germany and Austria and other countries close their borders … we will be ready to also close our borders at that very same moment,” Bulgarian prime minister Boyko Borisov said after talks between the three Balkan leaders in Sofia.

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Over past months, non-EU member Serbia has been swamped by asylum seekers on their way to northern Europe, though Bulgaria and Romania have been much less affected.

Mr Juncker’s office said the mini-summit was needed to foster greater cooperation “in view of the unfolding emergency”.

European Commission urges states to ‘play by the rules’

In an interview published on Sunday by the German newspaper Bild, Mr Juncker urged countries to stop handing on asylum seekers to neighbouring states in chaotic conditions.

States “must take care to uphold orderly procedures and conditions”, he said.

“The European Commission expects everyone to obey the rules of the game if we don’t want to put Schengen at risk,” Mr Juncker said, referring to the EU’s border-free zone.

The EU is facing record arrivals with more than 47,500 people in the last week entering Slovenia, which has a population of just 2 million, and 48,000 entering Greece, which has a population of 11 million, according to official figures.

With winter looming, Amnesty International warned of a humanitarian disaster if asylum seekers are stranded at borders.

Slovenia is seeking help after becoming the main entry point into the Schengen zone after Hungary sealed its southern borders with coils of razor wire.

Slovenia has asked Brussels for 140 million euros ($215 million), in addition to police backup and logistical support.

It says that if no help emerges, it may have to build its own border barrier with Croatia.