Klitschko, the brother of opposition leader Vitali Klitschko, said the situation in Ukraine had spiraled out of control because of government provocation.
"My own people are killing each other. It's something worse than a dream," Klitschko said in a telephone interview with The Associated Press from Hamburg. "I am just speechless. I can't believe something like this is happening in my country."
Klitschko, who was in Kyiv last month when the demonstrations were still peaceful, claimed the deaths in recent days were part of a government plan to break the opposition by forcing the Army to come in and impose martial law.
He called on the world to hold Yanukovych responsible for the violence, which he compared to some of the worst actions of dictators of the past.
"The way he acts is as a terrorist," Klitschko said. "If he's going to keep doing what he's doing he definitely put himself in the footsteps of (late Libyan dictator Moammar) Gadhafi.
Klitschko said he was horrified at the scenes of violence in Kyiv, and video of bodies lying side by side on the edge of the demonstration. He said demonstrators had been peaceful for three months, and that the government instigated the fighting that left many dead and buildings in flames.
"It's brothers killing brothers, which is not acceptable," he said. "There is enough video documentation online you can see in daylight people getting shot just standing there. I'm not talking about one, we're talking about 100 people in different ways killed, either by torturing or snipers."
Klitschko talked Thursday night from Hamburg, where he is training for an April 26 title defence. His brother, Vitali, was also a longtime heavyweight champion but resigned his title last year so he could concentrate on politics in Ukraine.
Klitschko said he talked to his brother a few hours earlier Thursday, and he remained unafraid. The conversation was short and chaotic, he said, but his brother's will remains unchanged.
"I asked, 'How are you doing?' He said, 'I'm alive.'"
"I said, 'Thank you.'"
Video footage on Ukrainian television showed scenes of protesters being cut down by gunfire, and teams of protesters carrying bodies away on sheets of plastic or planks of wood. Protest doctors accused government snipers of killing at least 70 people and wounding hundreds others.
"Three months ago nobody would have ever thought it would happen like this," Klitschko said. "The way it went you could see like in a chess game that it was certainly planned from the side of power from the side of president."
Klitschko praised Ukrainian skier Bogdana Matsotska for pulling out of the Olympics in protest at the government action, and said other Olympians should find their own ways to make a statement.
He expressed hope that other nations would come to the aid of the demonstrators by putting pressure on the government.
"The resolution is out there, it's always out there," he said. "It just can't happen with the president still in office."Suggest a correction