Ukraine's former prime minister Yulia Tymoshenko has gone on trial in a case that has raised concerns in the West over the government's commitment to democracy and the rule of law.
Ms Tymoshenko, now a top opposition leader, has been charged with abuse of office in signing a deal with Moscow to buy Russian natural gas at prices investigators said were too high.
She denies the charges, and describes them as a political plot by her rival, president Viktor Yanukovych, to keep her out of upcoming parliamentary and presidential elections.
The United States and the European Union have condemned the probe against Ms Tymoshenko and a number of her top allies as selective prosecution of political opponents.
Ms Tymoshenko was greeted by about 1,000 supporters who had gathered outside the court, handing out posters emblazoned "Hands off Tymoshenko!".
Some of her supporters also packed into a stifling court room lacking air conditioning, shouting "Shame!" as the judge opened preliminary hearings in the case.
Ms Tymoshenko refused to stand up to answer the judge's questions and then demanded that he should be dismissed.
"I declare you a puppet of the presidential office," Ms Tymoshenko said. "You don't have the right to consider this case. You are fully integrated into a system of political repressions directed by authorities."
Ms Tymoshenko was the central figure in the 2004 mass protests dubbed the Orange Revolution that threw out Mr Yanukovych's fraud-tainted election victory. She was defeated by Kremlin-friendly Mr Yanukovych in the February 2010 presidential election and later lost her premier's job.