The former prime minister of Ukraine, Yulia Tymoshenko, has gone on trial in Kiev charged with abuse of power while in office.
She is accused of exceeding her authority by signing a gas contract with Russia in 2009 after Moscow had briefly cut supplies.
It is alleged that the deal caused Ukraine severe financial loss.
Mrs Tymoshenko has described the proceedings as a plot by President Viktor Yanukovych to stop her standing against him in future elections.
She has asked the European Court of Human Rights to decide whether the charges are politically motivated.
About 1,000 of her supporters gathered outside the court in Kiev, which was ringed by police, the BBC reports.
The charges are not the first to be brought against the former prime minister. In December, she was charged with misusing 320m euros received by the government in 2009 for the sale of carbon credits.