Already tense relations between Romania and the EU threatened to deteriorate further on Thursday, when Brussels hit back at a decision by Bucharest to launch criminal investigations against two of its top officials.
Brussels denounced Romania's decision to launch a probe against the EU Commission's deputy president Frans Timmermans and Justice Commissioner Vera Jourova for alleged abuse of office and making false statements about Romania.
The investigation is being handled by a special panel of magistrates set up just four months ago despite fierce criticism by Brussels.
"We learned via the media about the fact that the Romanian authorities launched a criminal investigation against several commission officials concerning actions performed in their official capacity and the exercise of their duties," Commission spokesman Margaritis Schinas told a regular news briefing in Brussels.
"Of course, we do not comment on national judicial proceedings, but we would nevertheless like to remind Romanian authorities that all Commission officials - when they're doing their jobs - are subject to the jurisdiction of the European Court of Justice, and that the national authorities have no jurisdiction in these matters," Schinas said.
The latest spat erupted after the government-friendly Romanian website, luju.ro, accused Timmermans and Jourova of making false statements within the framework of the Cooperation and Verification Mechanism (CVM), a special system for monitoring the progress Romania is making in a number of areas, such as the judiciary and the fight against corruption.
Romania has been subject to annual CVM monitoring since it joined the bloc in 2007.
Timmermans has been highly critical of proposed judicial reforms by Romania's ruling Social Democrat Party or PSD, which Brussels sees as a threat to the independence of the judiciary and the rule of law.
The issue has overshadowed Romania's assumption of the EU's six-month rotating presidency in January.
At the end of last year, PSD chief, Liviu Dragnea, sued the Commission over accusations of corruption by its OLAF anti-fraud office.