Hundreds of refugees were left stranded in the fields along Serbia's border with Hungary last night (Tuesday) after Budapest closed the frontier, provoking fierce condemnation from the UN and human rights groups.
After Hungary declared a state of emergency on its border, police dragged a 13ft-high gated fence laced with barbed wire across the motorway into Serbia, a route for tens of thousands of migrants this summer.
Serbia accused its northern neighbour of treating the country "like a concentration camp", while a spokesman for the UN refugee agency described the move as "alarming".
As night fell, migrants set up tents in the fields that were filled with the detritus of an exodus: clothes, shoes, nappies, half-eaten tins of food and excrement. Some migrants started a hunger strike that they declared would not end until the border opened.
"No food! No water! Until open border!" they chanted. Among them was Moaz Hamar from Syria, who said: "This door will open. We travelled from Syria, came by sea in a rubber dinghy. Go back? I'm not going back. We are being treated like animals."
On the motorway sat a queue of lorries. "Just shoot them," said one driver, mimicking a machinegun.
After Hungary passed laws making crossing the border illegally punishable by three years in prison, 174 people were arrested over the course of the day, with 60 accused of cutting or damaging the fence.
While some tried to circumvent the wire wall by finding holes further along the border, others plotted new routes into Europe, including via Croatia, raising fears of casualties from mines laid during the Balkan war in the Nineties.
"There are more than 50,000 mines, but they do not know about that," said Daniel Szatmary, the co-ordinator of International Relationship for Peace, a volunteer group that gives food and water to migrants.
Hungary said it also planned to build a fence along its border with Romania.
The stand-off came amid continuing divisions in Europe over how to handle the crisis. Germany briefly suggested that poorer central and eastern EU states who refused to accept refugee quotas should be punished by cuts to their EU development grants.
Thomas de Maiziere, Germany's interior minister, said it was time to "talk about ways of exerting pressure", but drew a furious response. A senior government official from the Czech Republic said the German threats were "empty" since they had no legal foundation but were "very damaging".
Angela Merkel, the German chancellor, later rowed back on the suggestion while calling for an emergency summit to forge consensus in the debate. "Time is running out," she said, citing the need "to restore a European spirit".
A decision on whether to hold the emergency leaders' summit will be made tomorrow, while a separate extraordinary meeting of home ministers will now be held on Tuesday to discuss how to resettle 120,000 migrants under an EU quota system.