The EU demanded that Hungary "immediately withdraw" its new border regulations today after expelling foreigners to combat a resurgence of coronavirus cases.
Hungary closed its borders last night, with the exception of Hungarians returning from abroad who will have to be quarantined unless they can show two negative tests, and the visitor from Poland, the Czech Republic and Slovakia.
Brussels said the new rules were discriminatory and "not in line with basic principles of EU law" after motorists queued at the Austrian border last night.
The EU has long been in conflict with Viktor Orban's government over threats to the rule of law and the independence of the judiciary in Hungary.
Most European borders reopened in May and June, but many countries have seen an increase in recent weeks in cases where some have blamed foreign travel.
Cars queued at a border crossing near Nickelsdorf in Austria in the early hours of the morning when the Hungarian government closed its borders to foreigners
People are standing next to their cars and waiting to cross the border from Austria to Hungary on Tuesday morning
The EU today called on countries to coordinate border closings as the patchwork of controls across Europe is increasingly difficult to understand for its 460 million citizens.
"It is very clear that common European challenges require European coordination," said Commission spokesman Christian Wigand.
He added: “There can be no discrimination between EU citizens when it comes to travel restrictions. In the European Union there are clear rules on freedom of movement that every Member State must comply with. "
Commissioner Didier Reynders said he would raise the issue of "discriminatory" border measures with the government in Budapest.
"All measures that do not comply with these basic principles of EU law should of course be withdrawn immediately," he said.
Hungary accumulated 806 new infections in the last week, an alarming increase from 239 the week before and 220 the week before.
Nationalist leader Orban faces one of the biggest challenges of his 10-year reign after the economy slumped 13.6 percent annually in the second quarter.
While Hungary is one of the approved countries on the UK's "travel corridors" list, the new rule means that foreigners will not be allowed.
Exceptions to the entry ban apply to military convoys and humanitarian transit as well as business or diplomatic trips.
After talks with the Czech Prime Minister Andrej Babis on Monday, Orban agreed to allow Czech visitors who had already booked a vacation for September to enter the country.
The slight relaxation of the rules was later extended to Poland and Slovakia, the Hungarian Foreign Ministry said in a statement.
Visitors coming to Hungary are required to present a negative test no older than five days, which Budapest says is safe enough.
A line of vehicles going the other way to Austria when Hungary closed its borders to foreigners and ordered Hungarians to return to quarantine
An Austrian police officer inspects vehicles that line up in the early morning hours of Tuesday to enter the country from Hungary
Cabinet chief Gergely Gulyas said Hungarian citizens could only exit the 14-day quarantine if they present two negative tests.
"The number of infections has increased … and most of them come from abroad," Gulyas said at a press conference last week.
"We don't want to reinstate any lockdown measures," said Gulyas.
He said the border restrictions were necessary to get the school year started this week and to protect people as well as the economy.
Hungary's national police chief will have the power to grant exceptions in other limited cases.
Vehicles queuing at the border crossing earlier this morning as Hungary tries to stop an alarming resurgence of coronavirus cases
Gulyas tested negative for the virus last week after he and other officials gathered at a private event with a party spokesman who later tested positive.
Foreign Minister Peter Szijjarto also came under fire last week after he was spotted on a yacht in Croatia when he shared pictures that appeared to show him at work in an office.
Budapest will host the UEFA Super Cup next month between Champions League winners Bayern and Europa League winners Sevilla.
The government is considering different ways fans can join the game on September 24, Gulyas said.
The Champions League and Europa League finals were played behind closed doors, but UEFA is ready to allow limited participation in the Super Cup.
One possibility is that the fans at the airport would have to present two negative tests, would be transported directly to the stadium and back to the airport after the game.