A Ukrainian opposition leader and presidential candidate is recovering in hospital in Vienna after an alleged attempt to poison him.
Yushchenko is ahead in the polls
Viktor Yushchenko arrived in the Austrian capital a week ago after falling ill with what was thought at the time to be food poisoning.
But doctors found "chemical substances" inside the candidate, an aide said.
A presidential aide made light of the allegation, suggesting the candidate should have drunk vodka as a cure.
Giving details of the alleged poisoning on Friday, campaign manager Oleksander Zinchenko said there was "enough evidence to say that it was an attempt on [Mr Yushchenko's] life".
Austrian doctors were quoted as saying their patient's illness was due to both a serious viral infection and "chemical substances which are not normally found in food products".
In August, an attempt was allegedly made to force the candidate's car off a road as he campaigned in Ukraine.
Mr Yushchenko's campaign team said they had been expecting the authorities to resort to "strong-arm techniques" to ensure the victory of Prime Minister Viktor Yanukovich - the candidate favoured by the outgoing Ukrainian President, Leonid Kuchma.
"A month before their ouster, the authorities are ready to launch any kind of attacks to ensure their survival, including the elimination of competitors," the team said in a statement.
However, the deputy head of the Ukrainian presidential administration denied any wrongdoing.
"Let Zinchenko taste the food which is brought to Yushchenko," Vasyl Baziv was quoted as saying by Tribuna newspaper's website.
"That's what leaders did in the Middle Ages.
"I would recommend him to drink a hundred grams of vodka. If he had drunk that nothing would be wrong with him."
Mr Yushchenko is currently ahead of his main rival, Prime Minister Yanukovich.
However, analysts predict neither candidate will win outright in the first
round, due to be held on 31 October, forcing a second round in November.