Irina Gorbaseva / AP

Ukraine’s Nikolai Shmatko sculpting Tymoshenko and Yushchenko.

KIEV — Ukrainian presidential candidate Yulia Tymoshenko on Wednesday drove up tension ahead of Sunday's election, accusing rival Viktor Yanukovych of preparing to rig the vote through last-minute changes to election rules.

Yanukovych's Party of Regions pushed through the parliament an amendment to electoral rules that will scrap the requirement for a quorum of representatives of both contenders to approve the count at individual polling stations.

"Parliament has passed changes to the law … that wreck an honest presidential election, make it false, dishonest, unregulated," Prime Minister Tymoshenko said in a televised statement.

"This has been done because Yanukovych does not believe in his victory, and he wants to get a result only through falsification," she said.

She urged President Viktor Yushchenko not to sign the electoral rule changes into law and said she had invited ambassadors from the Group of Eight countries to an urgent meeting late Wednesday.

The Party of Regions had argued that the quorum could be abused by Tymoshenko's supporters if her representatives failed to turn up at the polling station, thus delaying the approval of the count or making it impossible altogether.

Yanukovych said he expected Yushchenko to sign the amendments into law, Interfax reported.

"I am certain President Yushchenko, who has also said many times that he is interested in carrying out honest elections in Ukraine, will sign it," Yanukovych told journalists while on the campaign trail in the eastern city of Luhansk.

Tymoshenko and Yanukovych are set for a runoff vote for president on Sunday after a bitter campaign in which she has openly insulted him and he has accused her of systematic lying.

Tymoshenko trailed Yanukovych by 10 percent in the first round of voting Jan. 17, but most observers say the outcome of Sunday's election is too close to call.