VIENNA, Dec. 11 (UPI) -- Vienna doctors treating the mystery illness of Ukrainian opposition leader Viktor Yushchenko have determined he was poisoned by dioxin, the BBC reported.
Yushchenko is being treated at a Vienna hospital Rudolfinerhaus for the illness he contracted in September as he was campaigning for the Ukrainian presidency.
The physicians said extensive tests showed a form of dioxin had been used on Yushchenko, the BBC said Saturday.
After becoming ill, Yushchenko was taken to the Vienna hospital where he underwent intense treatment for internal swelling and ulcers. He then developed back pain so severe he was fitted with a morphine drip into his spine, the Daily Telegraph reported.
The illness also left Yushchenko's face disfigured.
Yushchenko had accused Ukrainian authorities of trying to poison him. In the election, Yushchenko lost to Prime Minister Viktor Yanukov, however, Ukraine's Supreme Court voided the outcome of the vote. Another election is scheduled Dec. 26.
Dioxin is a hazardous substance produced during the industrial processes such as waste incineration, chemical and pesticide manufacturing and pulp and paper bleaching.