Russian-Israeli billionaire Roman Abramovich suffered poisoning symptoms following peace talks earlier this month in Kyiv, the Wall Street Journal reported on Monday.

According to the report, Ukrainian peace negotiators who joined the talks also experienced the same symptoms, citing sources familiar with the developments.

Abramovich’s spokesman confirmed the report to the British Broadcasting Corporation.

The WSJ sources blamed the attack on anti-peace activists in Russia who oppose talks to end the conflict that has been going on since Russia invaded Ukraine last month.

Abramovich and at least two senior Ukrainian negotiating team members showed symptoms of red eyes, constant and painful tearing, and peeling skin on their faces and hands. The sources said their conditions have improved since the outbreak, and their lives do not appear to be in danger.

Guardian reporter Shaun Walker quoted sources confirming the report adding that “Roman lost his sight for several hours.” He was treated in Turkey.

Rustem Umerov, a Crimean Tatar lawmaker, was another victim on the team who experienced the same symptoms.

A source close to Abramovich did not know who executed the alleged poisoning.

Western experts who investigated the attack said it is difficult to verify if a biological or chemical agent triggered the symptoms. They did not rule out an electromagnetic-radiation attack, sources said.

Ukrainian President Volodymyr Zelensky, who also met with Abramovich, was not affected. Zelensky’s spokesperson said that he had no information about any type of poisoning, according to the report.

Abramovich was one of the few Russian billionaires who has been outspoken about his attempts to urge the Kremlin to attain a peaceful resolution.

Last week, the WSJ reported that Zelensky requested that Biden refrains from sanctioning Abramovich, as Europe did to him and other tycoons. Zelensky told US President Joe Biden that he wished the Israeli-Russian billionaire could help mediate between Ukraine and Russia.

But unnamed US officials told the paper that they are unconvinced that Abramovich was helpful in the negotiations between Kyiv and Moscow. Intelligence assessments arrived at the same conclusion.