Czech President Vaclav Klaus sent a letter to his Ukrainian counterpart Viktor Yanukovych on Tuesday, asking him to affirm that the trial against the country's former prime minister, Yulia Tymoshenko, is not politically motivated, the Czech presidential spokesman said. "I would like to be sure that we are not speaking about a political trial in the case of former Prime Minister Tymoshenko, and that this trial will not be used to resolve personal or political differences existing in Ukraine's political scene," the letter reads. Tymoshenko is being tried on abuse of office charges in connection with a gas contract signed with Russia in 2009. She was taken into custody on Friday during a court hearing. She says the charges against her are politically motivated. Kiev has accused Tymoshenko, currently Ukraine's opposition leader, of signing the gas deal, which was "disadvantageous" to the country, without approval from her government. The Kiev court dismissed on Monday an application by the former prime minister's lawyers to revoke her arrest. Tymoshenko's arrest has sparked international criticism, with a number of foreign governments and human right groups, including Washington-based Freedom House, as well as the head of a European Commission delegation to Ukraine denouncing the court decision. The Russian Foreign Ministry has issued a statement, saying that "all the deals on gas supplies were drawn up according to the legislation of the two countries and international law." On Sunday, the court banned mass gatherings near the court building and the pretrial detention center where the opposition leader is being held after Tymoshenko supporters set up tent camps at the sites to protest against her arrest.