Bulgarian watchdog fails to prove six firms fixed oil prices

SOFIA, March 29 (Reuters) - Bulgaria's anti-monopoly commission said on Wednesday it had not proved price fixing between six fuel retailers after an investigation.

In October, the commission accused Lukoil Bulgaria, part of LUKOIL, Shell Bulgaria, part of Royal Dutch Shell (LSE: 0LN9.L - news) , OMV (IOB: 0MKH.IL - news) , Eko Bulgaria, unit of Hellenic Petroleum, Petrol and Nis Petrol, controlled by Russia's Gazprom Neft of collaborating to fix retail prices of diesel and gasoline.

All the companies denied wrongdoing.

"No sufficient evidence has been found in the proceedings," the commission said in a statement on Wednesday.

The commission, however, imposed measures on the retailers, obliging them to stop any exchange of information among themselves and guarantee within one month that they would fire staff that did not adhere to confidentiality requirements.

(Reporting by Angel Krasimirov; editing by Radu Marinas and Susan Thomas)