Ukrainian opposition leader Vitali Klitschko said the country's president was "responsible for murders and terror against civilians."
In a video address to the Ukrainian people, the former heavyweight boxing champion alleged the government of Viktor Yanukovych had ignored the demands of pro-West demonstrators since November. Klitschko claimed the "actions of authorities" were the "main reason" for the violence.
"A peaceful protest Ukrainian people continued for three months. They came out to defend their rights," said Klitschko, who heads the UDAR party. "Only Yanukovych is responsible for murders and terror against civilians. And only he can stop it."
Dozens of people have been killed in Kiev since Tuesday, which was Ukraine's bloodiest day since winning its independence from the Soviet Union in 1991.