Ukraine's anti-corruption bureau said on Monday that it was conducting a large-scale operation to uncover corruption in the country's energy sector.

"The activities of a high-level criminal organization have been documented," the bureau said about the investigation which involves 1,000 hours of audio recordings and took 15 months of work.

"Its members have built a large-scale corruption scheme to influence strategic enterprises in the public sector, in particular JSC 'Energoatom'," according to the post on the Telegram messaging app.