Austria's interior minister has threatened to sue Hungary if it refuses to take in refugees who had crossed their shared border.
European rules widely ignored since last year state refugees must seek asylum in the first EU state in which they set foot.
Hundreds of thousands of refugees travelled from southern European countries further north to Austria, Germany or Sweden, making it impossible to implement the so-called Dublin.
Countries in central and eastern Europe, including Hungary, have opposed any European attempts to force states to accept returned refugees or introduce a quota regime.
The Hungarian government has previously declared the Dublin agreement finished.
When asked about Hungary's refusal to take back refugees, Austrian interior minister Wolfgang Sobotka said: "States or groups of states that permanently break the law have to expect legal consequences.
"In that case, the [Austrian] republic must sue. The republic must see that the European Union acts according to the law, full stop."
Austria initially welcomed large numbers of refugees from the Middle East and Afghanistan. However, the government started to toughen its asylum rules earlier this year and introduced an annual limit on the number of asylum requests it accepts.
Those steps, widely criticised by human rights groups and the European Union, came after support for the far-right Freedom Party (FPO) in opinion polls surged ahead of the ruling centrist parties.
The FPO's candidate might also win presidential elections on 2 October on an anti-immigration platform to become Europe's first far-right head of state.
The UK Government has announced it will build a 13ft wall in Calais to block refugees from crossing the channel.
The 13ft high barrier will stretch for one kilometre along the dual carriageway approaching the port and is designed to stop refugees from climbing into lorries and other vehicles.
Additional reporting by Reuters
