This is a unique case, a European Commission source said, adding that all countries that the EU had been enlarged to had safeguard clauses but they were never activated.

On Monday, the Commission announced that the college of commissioners entirely supported the activation of Article 39 of Croatia's accession treaty which will formally occur in the next few days unless Croatia undertakes steps that would justify this decision to be reviewed.

Vice-President Viviane Reding, President Jose Manuel Barroso and EC Enlargement Commissioner Stefan Fuele informed the college of commissioners about the situation and have received full support for future actions. As such, if there is no development in events in Croatia that would justify the situation to be reviewed, procedures foreseen in Article 39 of Croatia's accession treaty will be initiated soon, Reding's spokeswoman Mina Adreeva told reporters.

The process is being initiated because the Commission considers that Croatia has breached the European Arrest Warrant (EAW) when it adopted a law dubbed "Lex Perkovic" which limits the application of the EAW to crimes committed after August 2002.

The situation in Bulgaria and Romania cannot be compared to Croatia because those two countries entered the European Union unprepared, which led to post-accession monitoring, the so-called Verification Cooperation Mechanism (VCM), being applied. But they too were never punished within the framework of that mechanism. Bulgaria was punished in July 2008, a year and a half after joining the EU, and had EUR 500 million suspended due to its poor efforts in the fight against corruption and managing EU funds which it did not utilise in the pre-accession period. That suspension was lifted after one year but Bulgaria did not manage to utilise those funds because the deadline for their absorption had expired.

Romania was never punished even though it had received several cautions. Hungary too was the target of the Commission's reprimand in 2011 because of its media legislation. However, after being cautioned by the Commission, Hungary undertook steps to correct its legislation and sanctions were not imposed.