Tymoshenko's Western supporters accused Kiev of political bias when a court sentenced her to seven years in prison for abusing her authority during negotiations regarding a 2009 gas deal with Russia's Gazprom.
Russian Prime Minister Vladimir Putin had said he was puzzled by the prison sentence because the 2009 deal is still on the books. European leaders, meanwhile, said they might break off integration talks with Kiev over the issue.
Tymoshenko faced further questioning Friday on a new criminal investigation related to charges she embezzled $405 million, Russia's state-run news agency RIA Novosti reports. She's accused of embezzling money owed to Russia to pay for the natural gas.
"Who is going to be responsible for this $405 million owed to Russia's defense minister? Who is going to answer for it?" asked Ukrainian Prime Minister Nikolai Azarov.
The embezzlement charges carry a maximum penalty of 12 years in prison. Ukrainian lawmakers have considered proposals that would change the penalties for economic crimes, however.
Deputy officials from Tymoshenko's opposition party, All-Ukrainian Union "Fatherland," were quoted on her Web site as saying the embezzlement charges were "absurd."