SOFIA: Bulgaria, Romania and Serbia Saturday threatened to close their borders if EU countries stopped accepting migrants, as European leaders prepared for a mini summit on the continent’s worst refugee crisis since World War II.

Bulgarian Prime Minister Boyko Borisov said the three countries wanted a Europe-wide solution to the crisis but were not prepared to become a “buffer zone” for the tens of thousands of new arrivals.

The Bulgarian, Romanian and Serbian premiers held talks in Sofia on the eve of a meeting called by European Commission chief Jean-Claude Juncker, who has been urging a cross-border approach to the crisis, which has seen 670,000 people arrive on Europe’s shores this year.

The influx has prompted EU member Hungary to close its borders with Serbia and Croatia to halt the flow of new arrivals, and Slovenia has threatened to do likewise.

Borisov and his Serbian and Romanian counterparts said the best solution was commonly-agreed action across Europe, but warned that if other EU countries followed Hungary’s lead, they would have to act.

“All three countries, we 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,” Borisov said after the talks with his Romanian and Serbian counterparts.

“We will not let our nations become a buffer zone of the migrant flows that will become stranded between Turkey and the fences built up from Serbia.”

Over past months non-EU member Serbia has been swamped by migrants on their way from Greece and Macedonia to northern Europe, though Bulgaria and Romania have so far largely remained on the sidelines of the influx.

Hostillity toward new arrivals has been growing in Germany and Sweden, Europe’s most sought-after destinations for asylum seekers, lending increased urgency to efforts to get other EU members to accept a grater share of the arrivals.

Police in Sweden said a planned refugee home, around 90 kilometers (60 miles) west of Stockholm, was torched Friday night in a suspected arson attack.

The building was vacant at the time but there have been a dozen such attacks since the start of the year and on Thursday a man armed with a sword killed two people in a racist attack at a Swedish school with many immigrant pupils.

Authorities in Germany have also reported mounting anti-migrant violence. On Thursday, prosecutors said police had foiled a far-right plot to torch migrant shelters in the southern town of Bamberg.

Germany, the EU’s top economy, has taken in the vast majority of the migrants landing in Europe this year, most fleeing conflict in Syria, Iraq and Afghanistan.

On Saturday, a new German law came into effect to speed up the expulsion of people deemed to be economic migrants and to restrict political asylum for Albanian, Montenegrin and Kosovan nationals to exceptional cases.