Clashes between supporters of Ukraine's jailed ex-prime minister Yulia Tymoshenko and police erupted in Kiev on Wednesday.
Police cordoned off central Kiev's Kreshchatik Street during a march by Tymoshenko supporters, but the opposition broke through police lines and began throwing stones and bottles at officers.
Police reinforcements have arrived at the scene.
Tymoshenko, 50, was arrested on August 5. She is accused of damaging Ukraine's national interests by signing "unfair" gas supply deals with Russia as prime minister in 2009. She faces up to 10 years in prison if convicted.
Tymoshenko has repeatedly denied all the charges brought against her, saying they are politically motivated.
