KIEV - Rivals in Ukraine's scandal-ridden presidential polls traded barbs on Monday in a live television debate in what is likely to be the climax of campaigning ahead of Sunday's decisive rerun vote.

Hundreds of thousands of supporters of opposition candidate Viktor Yushchenko rebelled against the result of a Nov 21 run-off vote which was marked by heavy fraud in favor of Prime Minister Viktor Yanukovich, forcing the Supreme Court to order the rerun.

The peaceful street protests, dubbed the "Orange Revolution", have given a strong boost to Yushchenko. But the crisis has also highlighted a historic faultline in the country between the nationalist west and Russian-speaking east.

At the height of the crisis, several eastern regions supporting Yanukovich threatened to hold a referendum on stronger autonomy from Kiev if Yushchenko was declared the winner.

Yushchenko said the Ukrainian people had finally won the chance to vote in a fair election on Sunday after the authorities stole 3 million of their votes.

"This year the Ukrainian people won their freedom, their right to live in a free and democratic country," he said in Ukrainian, facing his rival across a minimalist studio.

Viktor Yanukovich (AFP/Getty Images)

Yanukovich, speaking Russian, distanced himself from the authorities under outgoing President Leonid Kuchma and accused the opposition of uniting with him to steal the election.

"We witnessed how the authorities embodied by Kuchma united with representatives of the orange coup and made all those illegal decisions (overturning his victory)," he said.

In measured tones, Yanukovich boasted of his economic successes and his steps to boost pensions and salaries, while Yushchenko, equally measured, accused Yanukovich of being part of a corrupt political system.

Questions

Reflecting the dramatic changes in the Ukrainian political scene, the candidates traded questions in the debate -- in high contrast to their previous timid television encounter, in which they were allowed only to make statements on specific issues agreed beforehand.

In the first debate, Yanukovich, referring to a mystery ailment that has facially disfigured the 50-year-old Yushchenko, suggested he would be unable for health reasons to carry out the duties of president.

Since then, doctors have said Yushchenko was the victim of deliberate dioxin poisoning and it was not clear if Yanukovich would now bring the subject up again.

Viktor Yushchenko (AFP/Getty Images)

Yushchenko himself says he is fit to be president, but does not want his health to be a campaign issue.

"I expect voters' interest in this debate to be even higher than in the previous one," analyst Oleksander Lytvynenko said. The previous debate was watched by about half of Ukraine's adult population.

Ahead of Sunday's vote, candidates have had to adjust their electoral pledges to take into account issues raised by the "Orange Revolution".

Yushchenko, who wants Ukraine to become a Western-style democracy with a liberal economy free of bureaucratic red tape, has visited eastern Ukraine, promising state support to its struggling Soviet-era heavy industries and a more liberal approach to the Russian language dominant in the area.

Yanukovich looks to former imperial master Russia to further Ukraine's economic development.