Ukrainian presidential candidate Mr Viktor Yushchenko was poisoned with TCDD, the most harmful known dioxin and one contained in Agent Orange, a scientist who analysed his blood said today.
The tests showed the TCDD was pure and must have been concocted in a laboratory, lead investigator Mr Abraham Brouwer said.
The tests, confirmed by three labs in the Netherlands and Germany, also confirmed that Mr Yushchenko's blood contained 100,000 units of the poison, the second-highest concentration on record.
Doctors announced last weekend that the 50-year-old Mr Yushchenko was poisoned with a dioxin chemical that left him disfigured, but MR Brouwer told the Associated Press that his team has now zoned in on TCDD, the most hazardous of all the dioxins.
There are hundreds of dioxins and they are usually produced inadvertently during manufacturing processes that use chlorine, such as those for herbicides, paper and pulp bleaching. Waste incinerators also produce dioxins.