Opposition leader and former heavyweight boxer Vitali Klitschko says Ukraine's President Viktor Yanukovych is responsible for the violent unrest that has engulfed the country's capital Kiev.
Speaking to ITV News Europe Correspondent Emma Murphy in Kiev, Mr Klitschko said he was "very worried" for the future of his country.
Asked who he blamed for the conflict, he replied: "The man who has absolute power in our country - President Viktor Yanukovych".
Ukraine has experienced difficult days before but few have been so complex or so pivotal.
The Ukrainian government says it is is ready to use all tools available to restore order if violence and unrest continues.
These are difficult days for Ukraine, a country edging toward its second revolution in a decade.