Dr. Michael Zimpfer, the director of Vienna's private Rudolfinerhaus clinic, announced the findings to the public in a press conference this afternoon.
"After having completed our examinations, which we have conducted in the course of the past 24 hours, as well as after having conducted various blood tests, there is no doubt about the fact that Mr. Yushchenko's disease has been caused by a case of poisoning based on dioxin," Zimpfer said.
Zimpfer said Yushchenko's blood and tissue registered concentrations of dioxin 1,000 times above normal levels. He said the poison -- which can cause severe skin disease and liver damage if ingested -- was likely administered orally.
But Zimpfer said doctors are unable to say if the poisoning was deliberate. That, he said, is up to Ukraine's legal authorities to decide. "All our diagnosis says is that this is a case of poisoning. We will not comment further, it's really up to the legal authorities to decide what kind of poisoning this is," he said. "What we have found is a high level of dioxin in the body, presumably caused by oral administration."
However, Zimpfer later said doctors suspect another person may have been involved.
"It would be quite easy in fact to administer this amount [of dioxin] in a soup that contains cream, because of the issue of fat solubility. As relates to the circumstances as regards a criminal investigation, this doesn't fall within our purview. We have made a final diagnosis as well as an additional diagnosis that we suspect a cause triggered by a third party, there is the suspicion of third-party involvement," Zimpfer said.
Yushchenko's illness kept him out of the early stages of Ukraine's presidential election, and left his face pockmarked and badly disfigured. The pro-Western candidate in Ukraine's contested presidential race, he fell ill in early September and has repeatedly claimed that he was poisoned by political rivals.
Yushchenko will face Prime Minister Viktor Yanukovych in a 26 December rerun of the presidential election's second round. Ukraine's Supreme Court ruled the runoff poll last month was marred by fraud and canceled Yanukovych's declared victory.
(compiled from wire reports)[For more RFE/RL coverage and analysis of the political crisis in Ukraine, click here.]