An inquiry is to be reopened following confirmation that the Ukrainian presidential hopeful, Viktor Yushchenko, was the victim of dioxon poisoning.
At a news conference this afternoon in Austria, Dr Michael Zimpfer of Vienna's Rudolfinerhaus clinic said, however, that it remains unclear if this was the result of a deliberate act.
Mr Yuschenko had travelled to the Austrian capital for the tests.
He fell ill last September with an ailment that disfigured his face. Since then, he has repeatedly claimed that he was poisoned by political rivals.
Last month, he was defeated by his pro-Russian rival, Viktor Yanukovich, in presidential elections that he claimed had been rigged and which the country's supreme court subsequently annulled.
A re-run of the election is scheduled to take place on 26 December.