Photos posted on Telegram by Russia’s RIA Novosti news agency appear to show Russian billionaire Roman Abramovich in attendance at the talks in Istanbul on Tuesday.
The Chelsea owner was reported to have been poisoned alongside a Ukrainian who was member of the negotiating team during one of the earlier sessions.
But US official dismissed the reports, stating the two reacted to the environment.
Ukraine’s President Volodymyr Zelensky urged the US not hammer the Russian billionaire because he was going to be useful in the negotiation.
Kremlin spokesman Dmitry Peskov was quoted by RIA Novosti as saying that Abramovich’s participation at the talks on Tuesday had been approved by both Moscow and Kyiv.
A spokesman for the 55-year-old, earlier said Abramovich’s influence in negotiations to date between the two sides had been “limited”.