Presenting OLAF's 2008 annual report in Brussels, Franz-Hermann Brüner, the office's director-general, said Sofia "clearly has a long way to go" in fighting corruption.
"Some criminals are still dancing around us and the Bulgarian government, and I don't like it," Brüner said, identifying the courts rather than the prosecution as the weakest area. "Minor cases have been concluded, but not the prominent ones."
Last summer, the EU moved to suspend some €500m of funding for Bulgaria in the face of corruption scandals and Sofia’s failure to make sufficient progress on judicial reform (EurActiv 24/07/08).
"Major cases which led to the blocking of money are yet to be concluded, and these people are still walking around, even though the evidence against them has been proven by courts in other member states," he pointed out.
The OLAF chief cited Bulgaria's "very politicised system" as the main reason for this. "Younger officials are willing to make the changes, but we need to reduce political pressure on judicial authorities," he said.
Nevertheless, Brüner reserved some praise for Sofia's efforts to address the problem. "When we started, the glass was half-empty, but today it's half-full," he said, hailing recent "major changes" to the Bulgarian administration.
The lion's share (55%) of OLAF's active investigations last year concerned just six countries: Bulgaria, Romania, Belgium, Italy, Germany and the UK.
The report revealed that around €460m of EU monies were recovered last year as a result of OLAF cases. It cost €53m to run the office in 2008.
Asked to comment on the scale of the fraud from country to country, Brüner said it was "impossible" to compare exact figures "because countries receive different amounts of funding in the first place".
Problems persist in Romania
The OLAF chief reserved some of his strongest criticism for the Romanian judiciary, which has been slow to deal with many of the cases the EU office left on its desk last year.
"We are nowhere and need to do something. We want results. We want cases to be dealt with. We're still waiting for trials and the outcomes of those trials," he said, citing a lack of judges competent enough to understand complex economic fraud cases among the challenges facing Bucharest.
Brüner also lamented the "unacceptable" length of time it takes to see an end result of its investigations in general.
"Our problem is timing. Many of our cases take 5-10 years for judiciaries to complete. We need to baby-sit them right through to the end, or we won't be successful," he said.
In a separate development, the European Commission announced yesterday that its own report on fighting fraud will be published on 22 July.