Russian oligarch Roman Abramovich and members of the Ukrainian negotiation team suffered symptoms of suspected poisoning earlier this month after a meeting in Kyiv, the Wall Street Journal and the investigative outlet Bellingcat reported on Monday, citing people familiar with the matter.
Abramovich, who accepted a Ukrainian request to help negotiate an end to the Russian invasion of Ukraine, and at least two senior members of the Ukrainian delegation, were affected, the WSJ report said.
The billionaire businessperson has been recently slapped with sanctions by Western nations seeking to pressure Russian President Vladimir Putin over the invasion.
After a meeting in Ukraine's capital, Abramovich and at least two senior Ukrainian negotiators developed symptoms including red eyes, painfully watery eyes, and peeling skin on their face and hands, the sources said, according to the American newspaper.
It was not clear exactly who may have conducted the apparent attack, but those targeted blamed hardliners in Moscow seeking to disrupt ongoing talks to end the war, the Journal said.
Abramovich and the Ukrainian negotiators, including Crimean Tatar lawmaker Umerov, have since improved and their lives are not in danger, the people said.
A person familiar with the matter confirmed the incident to Reuters but said Abramovich had not allowed it to stop him from working.
Bellingcat said experts who examined the incident concluded: "Poisoning with an undefined chemical weapon" was the most likely cause.
Citing the experts, Bellingcat said the dosage and type of toxin used were not enough to be life-threatening, "and most likely was intended to scare the victims as opposed to cause permanent damage. The victims said they were not aware of who might have had an interest in an attack."
"It was not intended to kill, it was just a warning," Christo Grozev, an investigator with open-source collective Bellingcat, said in the Journal after studying the incident.
Grozev, who determined after an investigation that Kremlin agents poisoned Russian opposition leader Alexei Navalny with a nerve agent in 2020, saw images of the effects of the apparent Abramovich attack, but no samples could be collected in time for forensic experts to detect poison, the paper reported.
Ukrainian officials poured cold water on the report. Asked about the suspected poisoning, Ukrainian negotiator Mykhailo Podolyak said "there is a lot of speculation, various conspiracy theories." Rustem Umerov, another member of the negotiating team, urged people not to trust "unverified information."
A U.S. official said on Monday that intelligence suggests the sickening of Abramovich and Ukrainian peace negotiators was due to an environmental factor, not poisoning.
"The intelligence highly suggests this was environmental," the U.S. official told Reuters, adding: "E.g., not poisoning."
The official, who spoke on condition of anonymity, declined to elaborate.
Ukrainian President Volodymyr Zelenskyy said Sunday that his government had received offers of support from Russian businesspeople, including Abramovich, who owns and is seeking to sell Chelsea Football Club and has had longstanding links to Putin.
Zelenskyy told journalists that the businesspeople had said they wanted to "do something" and "help somehow" to de-escalate Russia's military assault on Ukraine that has left thousands dead.
Zelenskyy did not mention a suspected poisoning, and according to the Journal, the presidential spokesperson had no information about such an attack.
Western countries including the United States and the EU have imposed unprecedented sanctions against Russia over its invasion of Ukraine, including placing oligarchs and other individuals close to Putin on sanctions lists.
Last week the Wall Street Journal reported Zelenskyy asked U.S. President Joe Biden to hold off on sanctioning Abramovich, arguing that the Russian billionaire could play a role in negotiating a peace deal with Moscow.
The Kremlin has said Abramovich played an early role in peace talks between Russia and Ukraine but the process was now in the hands of the two sides' negotiating teams. The two sides are due to meet in Istanbul on Tuesday for the first face-to-face peace talks in more than two weeks.
Russian forces invaded Ukraine on Feb. 24 in what Putin calls a "special military operation" to demilitarize Ukraine. Ukraine and the West say Putin launched an unprovoked war of aggression.