Ukraine's former president, Viktor Yushchenko, lobbied on behalf of the interests of Swiss-registered gas trader RosUkrEnergo which robbed the country's gas supplies, opposition leader Yulia Tymoshenko said during a court hearing on Thursday. Tymoshenko, the country's prime minister briefly in 2005, and then again from 2007 to 2010, is currently on trial for abuse of office in Kiev over a 2009 gas deal she signed with Russia which investigators say was ruinous for the Ukrainian economy. "Yushchenko directly lobbied for the interests of RosUkrEnergo," Tymoshenko said. Yushchenko was the ex-premier's brother-in-arms during the 2004 liberal Orange Revolution and beyond, but relations soured towards the end of his presidency. "Gazprom [Russia's gas giant] delivered gas to Ukraine via the Swiss RosUkrEnergo the following way: RosUkrEnergo bought about 60 million cubic meters of gas from Gazprom every year, then on the Russian-Ukrainian border it sold some 50 million cubic meters to Naftogaz [Ukraine's energy monopoly], and exported the rest to Europe," Tymoshenko said. Last year, Gazprom wrote off an $810-million debt RosUkrEnergo owed it, while Naftogaz agreed to return 12.1 billion cubic meters of gas it allegedly confiscated illegally from the Swiss firm. In June 2010, the Stockholm Arbitration Tribunal ruled that Naftogaz owed RosUkrEnergo 11 billion cubic meters of gas and 1.1 billion cubic meters in fines.