Former Ukrainian President Viktor Yushchenko gave false testimony in a Kiev court on Wednesday saying he was not involved in disputed gas contracts with Russia, a high-ranking source in the Kremlin said. "Yushchenko is lying to his court... During his presidential term he personally wanted to gain political dividends and proposed to [Russian] President Dmitry Medvedev to personally sign a deal settling gas issues... But he was told that the issue was within the competence of the heads of the governments," the source said. Yushchenko was giving testimony on Wednesday in the trial over his one-time Prime Minister Yulia Tymoshenko, accused of abuse of office. "Moreover, in his later telephone conversations with Dmitry Medvedev, Yushchenko said he fully trusted Yulia Tymoshenko, that she had all the necessary powers and that he would support all agreements reached with Russia," the source added. Tymoshenko is on trial on abuse of office charges in connection with a "disadvantageous" 2009 gas deal she signed with Russia while she was premier of the former Soviet republic. She faces 10 years behind bars if found guilty. Yushchenko rejected a claim by Tymoshenko that he had called back the Ukrainian delegation involved in gas talks with Russia in late 2008. Tymoshenko says that if he had not withdrawn the delegation - which she headed - there would have been no subsequent cut-off of gas supplies to Ukraine by Russian energy giant Gazprom.