Sanctioned Russian billionaire Roman Abramovich and Ukrainian peace negotiators suffered symptoms of suspected poisoning earlier this month after a meeting in Kyiv, the Wall Street Journal reported 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 team, were affected, the WSJ report said.
Their symptoms included red eyes, constant and painful tearing, and peeling skin on their faces and hands, the WSJ report added.
Abramovich and the Ukrainian negotiators, including Crimean Tatar lawmaker Rustem Umerov, have since improved and their lives are not in danger, WSJ reported.
A person familiar with the matter confirmed the incident to Reuters but said Abramovich had not allowed it to stop him working.
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.Russian forces invaded Ukraine on February 24 in what President Vladimir Putin calls a "special military operation" to demilitarize and "denazify" Ukraine. Ukraine and the West say Putin launched an unprovoked war of aggression.