By Michael Krosnov

Former heavyweight champion Vitali Klitschko vowed to bring order to what he describes as a "fight without rules" in Ukraine, calling for early elections in which he plans to stand against President Viktor Yanukovych.

In an interview with AFP, Klitschko also revealed he had held secret talks with Ukraine's hugely powerful oligarchs and tried to win their support for the mass protests against Yanukovych.

He also said he did not rule out inviting the currently jailed former prime minister Yulia Tymoshenko to become his head of government should he be elected president.

Ukraine has been rocked over the last month by the biggest protests since the 2004 Orange Revolution after Yanukovych infuriated pro-European Ukrainians by ditching a pact for closer ties with the EU.

Klitschko, the leader of the UDAR (Punch) party, has been at the forefront of the protests in a sometimes unlikely triumvirate of opposition leaders alongside the ally of jailed ex-premier Yulia Tymoshenko, Arseniy Yatsenyuk, and the nationalist Oleg Tyagnybok.

"Ukrainian politics today is a fight without rules," he said.

But he added that in the future "it must operate under the same rules as a sport, any violation of the rules leads to disqualification."

The 42-year-old on December 17 resigned his WBC heavyweight title to devote himself to politics, vowing "to knock out" Yanukovych in presidential polls that he wants to be held in March 2014, one year ahead of schedule.

Klitschko reaffirmed his call for the early polls, saying he will make Ukraine a parliamentary republic with presidential credentials reduced.

"I am fighting for a European country and not for the credentials. This policy is optimal for Ukraine," he admitted