Hungary sealed off a railway track yesterday used by tens of thousands of migrants to enter the European Union on foot, launching a crackdown promised by the right-wing government to tackle Europe’s worst refugee crisis in two decades.

With tough new laws and powers to turn back asylum seekers entering into force at midnight, helmeted police officers, some on horses, took up position across the track that traverses the border and has been used for months by migrants, many of them Syrian refugees, to enter the EU from Serbia.

A helicopter circled overhead and a cargo wagon, one end covered in razor-wire, was shunted into position to seal the border. The scene marked the first step in what Prime Minister Viktor Orban, one of Europe’s most vociferous opponents of immigration, says is a new policy of zero tolerance on the EU’s external border.

As night fell, migrants continued to cross, but in small groups queuing at an official pedestrian border crossing around a kilometre away. Workers from the United Nations refugee agency, UNHCR, brought blankets to protect them against the late summer cold.

A major flashpoint in Europe’s worst refugee crisis, Hungary has vowed to get to grips with the flow through the Balkan peninsula to the richer countries of northern and western Europe. Police have recorded over 190,000 entering Hungary this year, many of them fleeing conflict in the Middle East and Africa, including a record for one day of 7,437 by 4pm yesterday Their window of opportunity is rapidly shrinking as Hungary races to finish a 3.5-metre high fence the length of its 175-km southern border by October.

As of today, those who enter illegally over or under the fence risk arrest and imprisonment. Those who seek asylum face being held while their claims are fast-tracked, and possibly expelled back into Serbia after Hungary in July declared its impoverished neighbour a ‘safe country’ for refugees. Orban said he expected a high rate of deportations.

From today those who enter illegally, over or under the fence, risk arrest and imprisonment

“In such a case, if someone is a refugee, we will ask them whether they have submitted an asylum request in Serbia,” Orban was quoted as telling private broadcaster TV2. “If they had not done so, given that Serbia is a safe country, they will be rejected.”

The influx into Europe, by boat from North Africa across the Mediterranean or across Turkey and up the Balkan peninsula, has triggered discord and recrimination in the 28-nation EU, feeding anti-immigration sentiment.

Yesterday, two decades of frontier-free travel across Europe unravelled as Austria and Slovakia followed Germany in re-establishing border controls to cope with the influx. Austria said it would dispatch armed forces to guard its eastern frontier with Hungary.

Migrants leave the bus which came from Roszke camp in the village of Szentgotthard, Hungary yesterday.

Soldiers were already on the Hungarian border with Serbia yesterday and Orban drafted in hundreds more police, telling them to be humane but “uncompromising” in implementing the new laws.

Hungary’s National Transport Authority said it had closed Hungarian airspace in a 20-km band along the Serbian border up to a height of 1,350 metres to ensure the police, army and ambulance services could act effectively. International passenger flights were not affected.

The prospect of harsher measures and a long wait in Hungary as of today appeared to have spurred many migrants, who rushed by train, bus and taxi north through the Balkans having landed in Greece by boat and dinghy from Turkey.