Ukrainian lawmakers reopened their investigation Monday into Viktor Yushchenko's (search) allegations that authorities tried to kill him, after doctors in Austria determined the presidential candidate had been poisoned by dioxin.

The decision by a parliamentary commission followed a similar move by the country's prosecutor general on Sunday.

Yushchenko had asked investigators to wait until after the Dec. 26 runoff so as not to influence the outcome of the vote.

The commission will be led by Volodymyr Sivkovych, a lawmaker who has supported Prime Minister Viktor Yanukovych (search), Yushchenko's opponent in this month's election.

The vote is a rerun of the disputed Nov. 21 runoff, which the Ukrainian Supreme Court voided because of fraud. The results had Yanukovych winning.

"The results of the most recent expertise in Vienna are giving us grounds to renew our work," Sivkovych said. "However, we are not convinced that deliberate poisoning can be proved."

Yushchenko fell ill on Sept. 5 and was treated at the Rudolfiner clinic in Vienna. Doctors suspected poison but said they needed to conduct more tests. Yushchenko returned to the clinic last week after winning his battle for a new runoff.

Doctors said the new tests proved beyond a doubt that Yushchenko's illness, which caused dramatic facial disfigurement, was caused by a massive dose of dioxin, possibly slipped into his food.

Sivkovych urged Yushchenko to immediately hand over results of the latest tests.

An earlier commission led by Sivkovych investigated the case in October and decided that Yushchenko suffered a combination of a viral infection and several other diseases.

Prosecutors had closed the investigation before the Nov. 21 second round of voting, saying that they could not determine whether he was poisoned.

While high concentrations of dioxin, a byproduct of industrial processes, remain in his blood, doctors said Yushchenko's organs have not been damaged and he is fit for the campaign trail. His prognosis depends on which dioxin he ingested — which is as yet unknown — and in what amount.

Yushchenko praised Prosecutor General Svyatoslav Piskun on Sunday for reopening the criminal investigation. But he asked that it be conducted after the Dec. 26 rerun so as not to influence the vote "either positively or negatively."

"This question will require a great deal of time and serious investigation," Yushchenko said as he confirmed that his opponents wanted to assassinate or disable him rather than take the risk he would defeat the Kremlin-backed Yanukovych in the presidential election.

Yanukovych campaigners rejected suggestions that he could have been involved in the poisoning.

In an interview Monday with The Associated Press, Yanukovych accused the United States of interfering in Ukraine's internal affairs by financing his opponent's campaign.

"The United States' meddling into Ukraine's internal affairs is obvious," he said. "It is appearing as the financing of Yushchenko's campaign."

The Bush administration has spent more than $65 million in the past two years to aid nonprofit organizations in Ukraine, but U.S. officials say the activities don't amount to interference in Ukraine's election because they were not given to political parties.

Election officials are preparing for the third round of voting as state authorities allotted airtime to the candidates. Each candidate will receive two 30-minute segments in prime time on state-run UT1 TV between Dec. 21 and Dec. 24 to explain their platforms, Ukraine's Central Election Commission said.

The two candidates have also each been allotted an entire page in two official newspapers.

Commission official Serhiy Dubovyk warned that the Dec. 26 election was in jeopardy because the only company licensed to print the ballots can't produce them fast enough. The commission urged the parliament to either allow another company to print ballots or extend a Dec. 23 deadline set for when the printing must be completed.

Also Monday, Terry Davis, the secretary general of the Council of Europe, Europe's top human right's body, traveled to Kiev to discuss the election preparations.

Davis was scheduled to meet with outgoing President Leonid Kuchma, other top officials, Yanukovych and Yushchenko.