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. Last Updated: 07/27/2016

Investigators Delve Deeper Into the Activities of Yukos

Prosecutors appeared to be delving deeper into the affairs of the nation's largest oil company Tuesday, opening an investigation into Yukos' acquisition of a stake in the Yeniseineftegaz energy firm.

State-owned oil company Rosneft claims Yukos' 19 percent stake in the Siberian-based company was acquired illegally, Interfax reported. Yeniseineftegaz has licenses to develop potentially lucrative oil fields in Siberia.

Mikhail Khodorkovsky, chief executive of Yukos and the country's richest man, denied the shares were acquired illegally, questioning why the case was being investigated by the prosecutor's office and not an arbitration court.

"If they believe we obtained those shares illegally, they should take us to court," he told journalists Tuesday. Either Rosneft knew the claims would not stand up in court, or they were put up to it by a third party, he said.

Khodorkovsky, his companies and business partners have recently been involved in a series of legal proceedings.

Last week, Platon Lebedev, a billionaire partner of Khodorkovsky, was arrested amid allegations he defrauded the state of $283 million in the 1994 privatization of the Apatit fertilizer company.

Lebedev is chairman of the Menatep Group, a holding company that owns 61 percent of Yukos.

Khodorkovsky has said those investigations are "outside the framework of the law" and have nothing to do with the business operations of the company.

Opposition politicians and analysts said Lebedev's detention appeared to be a warning from the government to big business ahead of December's parliamentary elections.

Khodorkovsky, an increasingly influential business leader, has supported a number of opposition parties. Lebedev's detention came out of an investigation requested by lawmaker Vladimir Yudin, a member of the pro-Kremlin Fatherland-All Russia faction.