Bulgarian prosecutors were investigating more cases of alleged embezzlement of European Union funds by companies linked to controversial businessmen Mario Nikolov and Lyudmil Stoykov, identified in a report by the EU's anti-fraud office Olaf as the masterminds of a criminal group embezzling EU pre-accession aid.

Prosecutors were working on "10-11 cases" that lead back to Mario Nikolov, according to Margarita Popova, the head of a prosecutors unit investigating EU fund embezzlement, widely quoted by Bulgarian-language media.

The cases are based on tip-offs by Olaf and charges would be pressed once the prosecutors receive data from law enforcement agencies in other EU countries. The investigations are into alleged fraud using fake delivery of agricultural equipment, Dnevnik daily said.

Nikolov is already being investigated on similar charges in a case that, Olaf claims, saw old equipment exported to Germany and then sold back as new equipment. The Bulgarian companies defrauded more than seven million euro that way, Olaf said in a report in July 2008.

Nikolov's case is yet to go to court, but his alleged accomplice, Stoykov, has already been cleared in Bulgaria over insufficient evidence. Foreign nationals identified as accessories to the fraud have been convicted in Germany, while Stoykov still faces charges of money laundering.

Both Stoykov and Nikolov have claimed they were innocent.

Olaf's report said that the two businessmen had political protection, which is why they were not prosecuted. Stoykov was a major campaign contributor to President Georgi Purvanov's re-election bid, while Nikolov has donated funds to the Bulgarian Socialist Party.