Hungary's plans for a referendum on refugee redistribution quotas generated confusion and criticism in Brussels on Thursday, with the European Union asking Budapest to clarify its intentions.
Hungarian Prime Minister Viktor Orban unveiled plans for the referendum on Wednesday.
His country had from the start opposed the EU redistribution scheme, which foresees the relocation of 160,000 asylum seekers from migration frontline countries such as Italy and Greece to other EU member states.
"So far nobody has asked the people in Europe whether they accept or reject the mandatory resettlement of migrants," Orban said Wednesday.
The plan left the European Commission, the EU's executive, puzzled.
"We ... fail to understand how it would fit into the decision-making process which was agreed to by all member states, including Hungary, under the EU treaties," spokeswoman Natasha Bertaud told journalists in Brussels.
The redistribution scheme was approved by EU interior ministers in September, in a majority vote that overruled opposition from the Czech Republic, Hungary, Romania and Slovakia. Hungary and Slovakia have both vowed to challenge the measure in court.
Bertaud said the commission is now "awaiting further clarification" from Budapest on the referendum plans.
"We'll reserve value judgments until that time," she said, adding that it was too early to determine whether the referendum is in line with EU law.
Meanwhile, Italian Interior Minister Angelino Alfano criticized the Hungarian move, in comments to journalists ahead of talks with his EU counterparts in Brussels.
"Europe is a mix of rights and obligations, of solidarity and responsibility," he said, arguing that it was too easy to take the things you like "with a smile" and put issues you don't like to a referendum in the hope that they will be rejected.
Dutch Migration Minister Klaas Dijkhoff said it was "up to every country to organize their own internal deliberations" on decisions taken by the EU. His country is due to hold a referendum in April on a free trade deal struck with Ukraine.
"I don't want to criticize Hungary's internal political decisions," added German Interior Minister Thomas de Maiziere. "I just want to ... underline that we need coordinated European measures."