Chelsea owner Roman Abramovich had reportedly suffered suspected poisoning during peace talks held between Russia and Ukraine last month.
The Wall Street Journal have claimed suffered from symptoms including “red eyes, skin peeling, constant and painful tearing”.
Two Ukrainian peace negotiators were also said to have been affected.
The report claims the alleged poisoning was orchestrated by Russian hardliners who are against peace talks.
A source close to Mr Abramovich told the BBC he had now recovered and was continuing with negotiations to try and broker peace in Ukraine.
A statement from Dutch-based investigative journalist group Bellingcat on Monday read: “Bellingcat can confirm that three members of the delegation attending the peace talks between Ukraine and Russia on the night of 3 to 4 March 2022 experienced symptoms consistent with poisoning with chemical weapons.
“One of victims was Russian entrepreneur Roman Abramovich.”
Russian billionaire Abramovich has been put under sanctions by the UK Government, which has resulted in the sale of Chelsea.
The Raine Group is managing the sale process and the number of prospective bidders has been reduced to a shortlist.
A deadline of April 11 has been set for the parties to submit their final offers, along with a £1bn commitment to future spending required.
