Russian authorities have carried out more searches of an institution linked to the former Yukos oil empire as they probe possible embezzlement and money-laundering by Yukos employees.

They searched the Open Russia foundation Thursday, which was established by former Yukos chief Mikhail Khodorkovsky. A Moscow court has already sentenced him to nine years in prison on fraud and tax evasion charges.

Investigators also searched the offices of a member of Khodorkovsky's legal team, Anton Drel.

Critics of President Vladimir Putin call the Khodorkovsky prosecution and imprisonment retaliation for the oil tycoon's support of Russia's political opposition, a charge Kremlin authorities deny.

A court recently rejected Khodorkovsky's appeal, but reduced his prison term by one year.

Some information for this report provided by AFP and AP.