The boss of Ukrainian state energy company Naftogaz has reportedly been detained in connection with a corruption investigation.
Yevhen Bakulin took up the chief executive job in 2010 under ousted president Viktor Yanukovych.
Naftogaz has declined to comment on his alleged detention.
Police are said to be carrying out three separate probes into suspected corruption in the gas industry – that may have cost the Ukrainian state billions of euros.
Naftogaz is responsible for the import and distribution of Russian natural gas in Ukraine.
It also holds a monopoly on the shipment of gas from Russia’s Gazprom, via Ukraine, to Europe.