Hungary has suspended a key EU rule that says it must take back asylum seekers who first enter Hungary but travel on to other countries.
A government spokesman said the decision had been made because Hungary is overburdened by illegal immigration.
The announcement comes just days after Hungary announced a plan to erect a border fence against migrants.
Hungarian officials say that more than 60,000 people have entered the country illegally this year.
"Hungary has used up the capacities at its disposal," said a Hungarian government spokesman on Tuesday.
"The situation requires fast action; in this escalated situation Hungary needs to take a move ahead of EU decisions."
The EU has called on the Hungarian government to immediately clarify its position.
A spokeswoman for the European Commission added that Hungary had said that the suspension was for a "technical reason".
"The Commission has asked Hungary for immediate clarification on the nature and extent of the technical failure."
Hungary's government has suspended a core principle for handling asylum claims in the EU called the Dublin Regulation.
It says that the responsibility for examining an asylum seeker's claims usually lies with the first EU country that the migrant reaches.
If the migrant travels to a second EU nation, they can be sent back to the entry country to have their asylum claim processed.
The Dublin Regulation has already caused tension in the EU and is under review.
Finland and Germany are among several countries that have stopped sending migrants back to Greece after the country complained that it was being inundated with asylum applications.
Critics say that Tuesday's announcement is the latest anti-immigrant rhetoric from the Hungarian government.
It has already announced plans to build a wall to run the length of the 175km (109-mile) border with Serbia.
A recent government billboard campaign with messages such as "If you come to Hungary, don't take the jobs of Hungarians!" has also caused controversy.
The poster campaign is part of the government's efforts to win public support for tough new immigration laws that are expected soon.
In January to March 2015, Hungary had 32,810 new asylum applicants. It had the second-highest number of applicants in the EU after Germany.