The EU took the Czech Republic, Hungary and Poland to the bloc's top court yesterday over their refusal to accept quotas for asylum-seekers, setting up a new clash between Brussels and key eastern states.
The move shows the determination in Brussels to enforce the controversial scheme launched at the height of the migrant crisis in 2015 to share 160,000 refugees around the bloc and ease the burden on Greece and Italy.
"The European Commission has today decided to refer the Czech Republic, Hungary and Poland to the Court of Justice of the EU for non-compliance with their legal obligations on relocation," the commission said in a statement.
There was no immediate reaction from Prague, Budapest or Warsaw, but all three have previously said the quotas are part of attempts by Brussels to limit national sovereignty.
Brussels launched so-called infringement proceedings against the three countries in June for failing to take in any refugees under the quota system, and warned them last month of further action.
They face heavy fines for failing to comply with any eventual ruling by the Luxembourg-based European Court of Justice.
The ongoing row over the quota scheme has held up efforts to reform the bloc's asylum system, which leaders are supposed to be discussing at an EU summit in Brussels on December 14-15.
The EU's "relocation" scheme is now wrapping up having moved 32,000 out of an originally planned total of 160,000, but it caused bad blood when it was forced through two years ago despite the objections of some countries.
The row also underscores a growing rift between western European states and newer, former Soviet-bloc states in the European Union over a series of issues from migration to democratic standards.