"I call on the whole of society to oppose corruption and crime and support the government's efforts to make its administration more efficient," Verheugen said in remarks made in German following a meeting with Prime Minister Sergey Stanishev.

Verheugen noted that the same problems had been raised with Bulgaria back in 1999 when it had first started negotiations to join the EU. At the time, Verheugen was the EU's Enlargement Commissioner.

"The fact that these problems exist in Bulgaria does not mean that they do not exist in the other member states as well," Verheugen acknowledged.

But the commissioner said that he was "worried about Bulgaria's image" and wanted to hear "positive news."

Bulgaria and neighbouring Romania joined the EU in 2007 but have since been placed under the strictest monitoring regime ever imposed on any bloc member.

In a recent report, the European Commission strongly condemned Bulgaria's failure to tackle corruption and its bad management of EU funds and froze 800 million euros (1.2 billion dollars) in subsidies amid corruption and fraud concerns.