Kyiv Mayor Vitali Klitschko has said he knows U.S. Donald Trump's personal lawyer Rudolf Giuliani for over 15 years and values him as the most effective mayor of the United States, as well as a big sport fan, who attended several fights involving the Klitschko brothers.

"And I am very worried about him, because I know that he is a big fan of Ukraine and is ready to do everything to see Ukraine as a democratic and modern country," Kyiv mayor told the journalists in the lobbies of Kyiv Smart City on October 1.

He said there have been no talks about former U.S. Vice President Joe Biden, just about Ukraine and Kyiv.

"I needed his advice because he has a lot of experience as mayor," Klitschko said adding that "he has never had business with the lawyer, never borrowed money from him or vice versa."

"I am not responsible for international politics, I am the mayor of Kyiv and responsible for my city," the mayor said.