Sanctioned Russian-Israeli 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 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 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 from 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.
The Russian oligarch, who is mostly known as the owner of English soccer club Chelsea, has been hit with sanctions by the European Union earlier this month as part of a package of measures targeting Russia and President Vladimir Putin's close allies.
The Wall Street Journal reported last week that Ukrainian President Volodymyr Zelensky has asked his U.S. counterpart Joe Biden not to sanction Abramovich, hoping the billionaire could use his close ties with Putin to facilitate ceasefire talks.
According to the publication, the U.S. Treasury Department was ready to impose sanctions on Abramovich earlier this month, but the White House halted the move.
Russian forces invaded Ukraine on Feb. 24 in what Putin calls a "special military operation" to demilitarize and "denazify" Ukraine. Ukraine and the West say Putin launched an unprovoked war of aggression.