Hungarian riot police officers fired water cannons and tear gas on Wednesday after hundreds of migrants tried to break through a gate at the newly reinforced border between Serbia and Hungary.

“Open! Open! Open!” the migrants chanted, as many covered their faces. About 50 riot police officers formed a barrier to prevent them from passing. A vehicle armed with water cannons stood nearby. Military helicopters hovered overhead.

At least 20 policemen and two children were injured, a Hungarian security official said.

Serbia’s prime minister accused Hungary of “brutal” and “non-European” behaviour towards migrants on their joint border and urged the EU to respond.

“We will not allow anyone to humiliate us. I call on the European Union to react, for its members to behave in line with European values,” Aleksandar Vucic told Serbian state television during a visit to the US.

“If the EU does not react, we will find a way to protect our borders and European values as well,” he said.

Earlier on Wednesday, Serbian minister for migration issues Aleksandar Vulin condemned Hungary’s use of water cannon and tear gas against migrants, saying Hungary had “no right” to do so, Serbian state news agency Tanjug reported.

“This is being thrown across the border line, which no state has the right to do and because of that I protest in the strongest terms,” he said on the border.

Hungary said on Wednesday it had detained 29 migrants during the clashes on the Serbian border, and said one of them was an “identified terrorist”.

Gyorgy Bakondi, a security adviser to prime minister Viktor Orban, said: “Police also captured an identified terrorist”, without giving any more details.

UN Secretary-General Ban Ki-moon has expressed shock and alarm at the treatment of refugees and migrants on the Hungarian border, adding that they should be treated with dignity and their human rights respected.

“I was shocked to see how these refugees and migrants were treated, it’s not acceptable,” Mr Ban told a news conference.

“All the countries have their domestic problems, but since they are the people fleeing the wars and persecutions, then we must show our compassionate leadership.

“They must be treated with human dignity and human rights,” he added. “That’s my consistent message to European and Asian leaders, wherever this migration and refugees are coming.”

Hungary’s decision to seal its borders and press criminal charges against migrants is reverberating across Europe, sending thousands of people on alternative routes through Croatia and other countries to reach Germany and other points in western Europe.

Croatia’s prime minister promised them safe passage, as long as they were only passing through the country.

Hungary moved, meanwhile, to close off another alternative by tightening its border with Romania. The ripple effects reached as far as Edirne, on the European side of Turkey, where police officers at a bus station near the city were blocking migrants who wished to walk to the nearby border with Greece and Bulgaria.

Romania summoned the Hungarian ambassador on Wednesday over Budapest’s plan to extend a border fence towards Romania to stem the flow of migrants.

Hungarian soldiers, police and engineers were marking out the path of a fence on the country’s southern border with fellow EU member Romania, preparing to extending the barrier already on the frontier with Serbia.

Building the fence has angered Romania, whose prime minister Victor Ponta on Wednesday said the move was counterproductive and was reminiscent of Europe in the 1930s.

Romanian deputy foreign minister George Ciamba summoned Hungarian ambassador Zakonyi Botond, the ministry said in a statement.

“The Romanian deputy minister reiterated the ministry’s position over building a fence between the two EU states, a gesture that is not politically correct and that contravenes the European spirit,” the statement said.

Meanwhile, Hungary announced that police officers had detained 519 people for illegal entry or damaging a border fence since new rules came into force a day earlier.

Authorities have opened 46 criminal cases so far, and the first suspects were to appear in court Wednesday afternoon, according to Gyorgy Bakondi, an aide to prime minister Viktor Orban.

Prosecutors in Szeged, Hungary, said four Iraqi citizens would appear in court for illegal crossing, in expedited proceedings. They were held after crossing the border through an opening in the fence that had been cut by others, Hungarian authorities said. One Iraqi was convicted and sentenced to expulsion.

On the Serbian side of the border, hundreds of migrants remained while still others kept arriving.

At the border town of Horgos, migrants who had slept in tents overnight lined up for food. There were just 11 toilets and two taps with running water for them. The temperature reached a sweltering 86 degrees Fahrenheit.

Mohamed Afar (23), who said he had left Damascus, Syria, after his shop there was bombed, said he and 13 relatives had raced to get into Hungary, but had failed to make it before the border was closed.

Now, he said, they were sheltering in an abandoned building once used by Serbian customs officials.

Border controls

“I’m hoping the border will open,” he said, adding that he was looking to Chancellor Angela Merkel of Germany to resolve the crisis. “I will wait. Maybe Ms Merkel comes to open it?

“The Hungarian government seems to have no mind or heart. Can’t they see all these families? There is nothing for us here. It smells and it’s dirty.”

Mr Afar said that he was desperate to take his two young children to Germany or to the Netherlands, but that he was quickly running out of money.

Hungary’s actions have had spillover effects throughout the region.

Buses that had been carrying migrants to Serbia’s border with Hungary from its border with Macedonia were instead diverted to Croatia, Serbian news media reported.

Croatia’s prime minister, Zoran Milanovic, said on Wednesday that migrants would be allowed to pass through the country, which is a member of the EU, but borders several countries that are not. “No one will block them,” he said. “No fences.”

But Milanovic, who faces a tight race in elections scheduled for mid-November, also made it clear that his country was a temporary stop, not a final destination, for the migrants.

The closing of Hungary’s borders has raised concerns among humanitarian groups that migrants seeking to get to Croatia could inadvertently cross through areas near the Hungarian-Croatian border that are littered with thousands of land mines left from the Balkan wars of the 1990s.

On Wednesday, Croatian demining experts were sent to the area where many migrants were arriving, Reuters reported.

The countries of the former Yugoslavia, which were torn apart by the wars, have thus far taken a tolerant and welcoming stance toward the migrants, who have viewed the region as a transit zone rather than a final destination.

But with Hungary’s decision to criminalise the breaching of its borders, countries such as Serbia and Croatia, which are relatively homogeneous and poor compared with some of their richer European neighbours, could soon confront a stream of migrants for which they are ill-prepared.

In northern Serbia, a short distance from the border with Hungary, hundreds of people spent the night outside or in temporary tents and expressed determination to enter Hungary, notwithstanding the new ban. Hundreds chanted “Open the door!” and several began hunger strikes.

On a visit to the border region on Tuesday, Aleksandar Vulin, the Serbian minister of labour, employment and social affairs, chided Hungary for refusing to abide by its agreements with Serbia and warned that the situation could spiral out of control.

In Croatia, the Right Party leader, Anto Dapic, told the local news media that he supported offering “temporary aid to women and children, but not young men who look like they just left the gym”.

Mr Dapic has aligned himself with countries in Eastern and Central Europe, like Hungary, which have argued that immigration is a matter of national sovereignty, and that the EU has no right to tell countries how many refugees they should take in.

As countries reinstate border checks, companies and business groups say they’re managing to deal with the delays.

Four German industry groups said in a joint statement on Monday that they supported that country’s temporary measures to avoid the situation spiralling out of control.

Deutsche Post AG, which owns the DHL express delivery service and is Europe’s biggest mail provider, said it’s keeping in close contact with authorities to respond to the rapid changes.

“Our network for road transport is still functioning according to plan,” said Raluca Witowski, a Deutsche Post spokeswoman. “Where necessary, we did adjust routes to avoid possible waiting times. We are also working on alternative plans to avoid, or at least minimise, any possible impact in the near future.”

It also emerged on Wednesday a Syrian refugee who was filmed being tripped up by a camerawoman as he fled police in Hungary with his young son has been offered a job in soccer coaching in Madrid, after his story caught the eye of a training school there.

Videos of the man falling over with a child in his arms as dozens of migrants tried to escape police on Hungary’s southern border with Serbia went viral on media and social networks last week.

The footage shows a camerawoman, who worked for a private television channel in Hungary and was later fired, sticking out her leg as the man ran past.

The head of a school for soccer coaches in Getafe, on the outskirts of Madrid, said staff tracked down the man after reading he had previously done a similar job in Syria.

“We got the idea to help a fellow football coach,” Miguel Angel Galan, who runs the school knows as Cenafe, was quoted as telling Cadenar Ser radio.

The radio station said the local administration would provide him with housing.

Neither the school or the Getafe town council responded to requests for comment, though Galan said on his Twitter account that the Syrian refugee, identified as Son Osama Abdul Mohsen by Cadena Ser, was due to arrive in Madrid at midnight on Wednesday.

He was travelling by train, Cadena Ser said, alongside the son he carried when fleeing police last week, Zaid. It added that the school and local authorities were working on getting the rest of the family to join them in Madrid.

Earlier, Germany cut its train link with the Austrian city of Salzburg, shutting down the main route into its territory for tens of thousands of people caught in Europe’s worst migration crisis in decades.

Around 1,200 migrants slept overnight at Salzburg station on camp beds set up in the car park.

Many more stayed in emergency accommodation across Austria, part of a massive backlog waiting for transport on to Germany.

Germany announced border controls on Sunday that slowed a rush of people over its border, relieving pressure on officials who have struggled to cope with the influx.

But the numbers of people waiting in Salzburg and other cities have strained resources in Austria.

“We had more than 2,000 refugees an hour ago. The station was about to be closed,” Wilfried Haslauer, governor of Salzburg province, said on Wednesday morning.

“Now the refugees have understood that no trains are running, and they are setting off on foot.”

Hundreds of people remained at the station, one witness said, but city officials said several hundred were walking towards the nearby border.

“We have only observed small groups and we have seen no people on the tracks,” a police spokesman said.

Rail traffic between Germany and Salzburg was halted in both directions on orders of the German authorities, a spokeswoman for the Austrian rail operator OeBB said, adding no details on the reason for the closure were immediately available.

A rush of people into Austria - almost all of whom hope to reach Germany - has slowed to a trickle since Tuesday, when Hungary barricaded its southern border against migrants trying to cross its territory.

Signal to the world

Austria introduced stricter border controls of its own on Wednesday, following Germany’s lead.

Both moves have effectively suspended a system of borderless travel within Europe known as Schengen, but Vienna has made clear that the checks will slow migrants rather than stop them altogether.

“These border controls should be an important signal to the world,” interior minister Johanna Mikl-Leitner told the broadcaster ORF late on Tuesday. “There can be no borderless flow of migrants.”

Austria and Germany have called for a European leaders’ summit to address the migration crisis, Europe’s worst since the war in the Balkans in the 1990s, and called for quotas for the redistribution of asylum seekers within the bloc, combined with stricter measures near its external border.

The proposals have faced opposition from Eastern European countries.

“At the moment, more than 2,000 are coming (into Germany) with normal train services,” Austrian chancellor Werner Faymann told ORF on Wednesday.

“But if 25,000 or 22,000 people are in emergency accommodation, then you see that a bottleneck has arisen from the controls.”

In the eastern province of Burgenland, which borders Hungary, a police spokesman said the border controls had started, but he confirmed that migrants arriving at Austria’s eastern border would not be denied entry.

“The police have set up a funnel here to obviously slow down the speeds and to selectively choose vehicles which fall into the inspection mechanism and inspect them,” a spokesman for the police in Burgenland said. “I’m sure no one will be sent back.”

Elsewhere migrants walked through cornfields into the European Union through Serbia’s western border with Croatia, opening a new front in the continent’s migration crisis after Hungary shut the main overland route.

Croatia said it was sending demining experts to the border area to identify minefields left on the frontier from the Balkan wars of the 1990s, the last time hundreds of thousands of displaced people marched across Europe.

Hungary’s decision to shut the EU’s external border with Serbia this week was the most forceful attempt yet by a European country to close off the unprecedented flow of refugees and economic migrants overwhelming the EU.

The route through Hungary has been the main one used by migrants who arrive first by dinghy in Greece and then trek across the Balkan peninsula to reach the EU’s frontier-free Schengen zone, most eventually bound for Germany.

With that route closed, thousands of migrants remain in the Balkans seeking other paths north and west, possibly through Croatia and Romania, both of which are in the EU but not in Schengen.

Hungary has placed a 3.5 metre high fence along the length of its border with Serbia.

Engineers and soldiers were marking out a path on Wednesday to extend the fence along the border with Romania, a plan that has angered Bucharest.

Reuters/New York Times