The trial of Ukraine's former prime minister Yulia Tymoshenko opened Friday with her accusing President Viktor Yanukovych of using the proceeding to keep her out of politics.

Ms. Tymoshenko, now a top Ukrainian opposition leader, is on trial for alleged abuse of power.

The former prime minister denounced the trial as a pre-arranged farce and accused the judge of being a “puppet” of Mr. Yanukovych, who, she said, is trying to bar her from challenging him politically.

Her supporters in the hot, crowded courtroom in the capital, Kyiv, shouted “shame, shame.”

Ms. Tymoshenko has been charged with abuse of office for signing a deal with Moscow to buy Russian natural gas at prices investigators said were too high.

If convicted, she would be barred from running in upcoming parliamentary and presidential elections.

Mr. Yanukovych narrowly defeated Ms. Tymoshenko in presidential elections last year.