Ukraine's presidential contenders on Saturday exchanged accusations of fraud and preparations for provocative acts at the crucial vote runoff due tomorrow.

The campaign headquarters of opposition leader Viktor Yanukovych, a frontrunner in the first round of elections, reported massive discrepancies between ballot papers and polling station numbers in the mainly Russian-speaking southeastern districts traditionally supportive of Yanukovych.

Campaign chief Mykola Azarov blamed Prime Minister and presidential candidate Yulia Tymoshenko's supporters for the conspiracy to make the papers invalid.

He said the campaign headquarters requested the Security Council, the Central Election Commission and the Prosecutor General's Office to inquire into the discrepancies. He said more efforts are needed to check ballot papers at other polling stations.

The Yulia Tymoshenko Bloc said on Saturday that members of Yanukovych's Party of Regions were preventing bloc representatives from joining commissions to oversee the vote count in the eastern Donetsk Region and filed complaints with the courts.

"Yanukovych's headquarters has activated its electoral fraud machinery," the premier's party said in a statement. "Party of Regions representatives, seeking to have full control of election commissions, have blocked Tymoshenko's representatives from joining them."

"This is a cynical attitude to the law and a one-hundredth proof that the Yanukovych team's hopes for election victory lie mainly with fraud, criminal schemes and outrageous violations of people's right to fair vote results," the party said.

The first deputy head of the Central Election Commission, Andriy Mahera, predicted on Saturday that the losing candidate will file a complaint with a court trying to influence the results.

"I am 99% positive that such a complaint will be lodged, and the final decision will be made in a court," Magera said as quoted by Ukrainian media.

KIEV, February 6 (RIA Novosti)