Russia's top investigative agency says it has filed money-laundering charges against a billionaire tycoon.

The Investigative Committee said Tuesday that Vladimir Yevtushenkov, the head of Sistema holding company, has been placed under house arrest.

The committee said the 66-year old Yevtushenkov is suspected of involvement in a money-laundering scheme involving oil assets in the Russian province of Bashkiria. Sistema owns the Bashneft oil company, which is based in Bashkiria.

Russian media reports have said that Russia's largest oil company, state-controlled Rosneft, has expressed interest in buying Bashneft. Rosneft is run by Igor Sechin, a powerful longtime assistant of President Vladimir Putin.

Yevtushenkov's holding also includes MTS, Russia's largest cellular company, among other assets. Forbes magazine has ranked him Russia's 15th richest man with an estimated worth of $6.8 billion.