MOSCOW (Bloomberg) -- Russian prosecutors filed suit to regain state ownership of the oil producer controlled by Vladimir Evtushenkov as government lawyers stepped up their campaign against the arrested billionaire.

The Moscow arbitration court froze the shares in OAO Bashneft, controlled by Evtushenkov’s OAO AFK Sistema, in connection with alleged violations during the privatization of the regional oil company, the prosecutor’s office said Sept. 26 in a statement on its website.

Evtushenkov was denied bail on Sept. 25, leaving the oil and telecommunications billionaire under house arrest over an investigation into money laundering. Evtushenkov, who has maintained his innocence, is the richest Russian to face criminal charges since Yukos Oil Co. founder Mikhail Khodorkovsky more than a decade ago.

“The articulation by the prosecutors of their intention to return the shares back to the government’s ownership is a new component,” Luis Saenz, head of equity sales and trading at BCS Financial Group, said by email. Sistema’s 78.8% stake, which carries an 86.7% voting interest, has been restricted from trading since July.

Khodorkovsky spent over 10 years in jail while his Yukos Oil was seized by the state, with the bulk of its assets acquired by Kremlin-controlled OAO Rosneft.

Share Offering

Khodorkovsky claims that Rosneft head Igor Sechin is behind the assault on Evtushenkov in order to eventually gain Bashneft. Rosneft denies any interest in Bashneft.

Prior to its legal troubles, Sistema had planned to hold a share offering for the oil producer in which it sought to raise at least $1 billion.

Bashneft ordinary shares fell 5.1% to 1,263 rubles at the close in Moscow. Sistema sank 21% to 17 rubles, the lowest since October 2009.

VTB Capital resumed coverage of Bashneft Sept. 26 with a buy recommendation after shares fell almost 50% since July 15, according to the research note.

The worst case for minority shareholders from a return to the state would be a cut in the dividend payout to 25% of profit, and worsening efficiency, according to the note. The payout cut would “still on our numbers suggest a robust” 8% yield for common shares and 11% for preferred shares, according to the research.

‘Justice Triumph’

The Moscow court will consider the General Prosecutor’s case on Oct. 9, according to the court website.

Sistema “is in the process of clarifying the situation,” it said in a statement. Bashneft said its operations are not affected so far, while the company’s registrar is clarifying whether minority shareholders can trade shares.

Bashneft, which produces about 350,000 bopd, was controlled by Russia’s Bashkortostan region until 2003, when a major stake was sold to entities linked with Ural Rakhimov, son of former Bashkortostan President Murtaza Rakhimov, according to Vedomosti and Kommersant newspapers.

Sistema spent about $600 million building blocking stakes in Bashneft and other regional energy assets in 2005, paying $2 billion more in 2009 to gain control.

In April, investigators opened a case linked to deals with Bashneft shares in 2002 to 2009, charging both Ural Rakhimov and Sistema’s Evtushenkov.

Russia’s Economy Minister Alexei Ulyukayev said Sept. 26 he was baffled by the plan to seize Bashneft shares. “I do not understand this decision,” he told reporters in Moscow.

Bashkortostan “certainly supports” the prosecutors’ suit to regain state ownership in Bashneft, the region’s President Rustem Khamitov said Sept. 26 in televised comments.

The privatization was illegal, the region “received zero rubles, zero kopecks as a result,” Khamitov said. “We would like justice to triumph and property to be returned to the state.”