Romania's government has reacted with outrage after Austria blocked its bid to join the visa-free Schengen zone.
Austria’s ambassador was summoned to explain a veto that Romanian officials called unjustified and an act of blackmail.
The Austrian veto stopped Romania and Bulgaria from joining Schengen in an EU vote on Thursday.
The Netherlands also voted against, but said its objection was to Bulgaria and not Romania.
Austrian Interior Minister Gerhard Karner justified his vote on the grounds of a migration crisis in south-eastern Europe.
Landlocked Austria has demanded EU action over tens of thousands of undocumented migrants arriving from the Balkans.
But Romania said it had nothing to do with this and accused Austria of playing political games.
“This result is completely unfair and devoid of any objective motivation,” Romania’s Foreign Ministry said.
It said that with Russia hoping to exploit discord, “Austria's behaviour represents an unwanted political signal regarding the EU's ability to act.”
Romania’s Deputy Prime Minister Hunor Kelemen accused Austria of “miserable blackmail”.
“Austria’s veto is unfair, immoral, lacking solid arguments, showing a miserable political game,” he said.
Austria’s ceremonial head of state Alexander van der Bellen also criticised his government’s veto on Friday.
“It’s right that Austria is in a difficult situation because of the very high number of asylum seekers. But the Schengen blockade does nothing towards a solution,” he said.
But the government said it was the wrong time to extend Schengen when border protection was not working well enough.
It said many Tunisians, Indians and others have landed in the Balkans and made their way to Austria over land.
“It’s wrong for a system that’s not working in many respects to be expanded further,” Mr Karner said before the meeting.
“In Austria, we’ve this year had more than 100,000 illegal border crossings — 75,000 of those are not registered."
However, Austria did not stand in the way of Croatia joining Schengen on January 1, when it will also adopt the euro.
Romania said it was not on the Balkan route and had shown its capacity to handle migration by taking in Ukrainian refugees.
Bulgaria too was unhappy at the EU snub, accusing the Netherlands of an “anti-European stance”.
Dutch Prime Minister Mark Rutte had raised fears about corruption by worrying aloud that people could “cross the border with a €50 note”.
The EU’s home affairs commissioner Ylva Johansson shared the two countries’ disappointment, saying it made the bloc look weak.
“When we are united in the EU we are so strong, we can achieve so much,” Ms Johansson said.
Hungary, which often irritates neighbours with its use of EU vetoes, meanwhile complained of double standards.
Foreign Minister Peter Szijjarto suggested there was less outrage at Austria in the media and European Parliament than there would be at Hungary.
“Where are now the MEPs concerned for the unity of the EU? Or the MEPs who want to abolish unanimous decision-making?,” he asked.
Bulgaria, Romania and Croatia are the only three mainland EU countries who are not part of Schengen.
The zone created in 1995 abolishes checks at internal borders, although they can be brought back to deal with security threats.
Austria has used this provision to tackle the Balkan migration route, imposing checks at the Slovak, Hungarian and Slovenian borders.
