Ukraine revoked the license of U.S. company Vanco International, a subsidiary of Vanco Energy Company, to develop and produce oil and gas on the country's Black Sea shelf last month. Tymoshenko earlier described the move as "plundering of Ukraine's mineral reserves" and accused President Viktor Yushchenko of lobbying for the U.S. firm.
"The Black Sea shelf was dishonestly...handed over to shadowy bodies. We, the government, are initiating an international investigation," she said.
Presidential spokesperson Irina Vannikova dismissed Tymoshenko's allegations as inappropriate, while Yushchenko demanded the license be returned to Vanco.
Vanco International signed a 30-year production sharing agreement with former premier Viktor Yanukovych's government in October 2007, covering the Prykerchenska area just south of the Crimean Peninsula.
Under the deal, the company received a 65% stake and Ukraine 35% at the prospecting and development stage. The sides were to go 50-50 with the launch of commercial production.
Vanco Energy Company is an integrated independent oil and gas company which operates its exploration and production activities through its wholly owned overseas subsidiary and subsidiaries of Vanco International Ltd.
