Russian billionaire Roman Abramovich has appeared at Turkish-led peace talks on the Russian war in Ukraine, hours after reports that he suffered poisoning symptoms earlier this month.

He was seen talking to Turkish President Recep Tayyip Erdogan and then sitting beside Mr Erdogan’s spokesman.

He is known to have spent weeks in a mediation role, flying between Moscow and Kyiv.

Sources said he and two Ukrainian negotiators suffered symptoms in Kyiv.

The Chelsea football club owner was said to have suffered sore eyes and peeling skin, but had now recovered, reports say.

A Wall Street Journal report suggested he and the Ukrainian negotiators had been targeted by Russian hardliners, but a Ukrainian presidential official later said the two Ukrainians were fine and one had said the story was false.

The talks in Istanbul got under way early on Tuesday, with President Erdogan opening the session calling for a ceasefire and peace: “Prolonging the conflict is not in anyone’s interest,” he told the two delegations at Dolmabahce Palace, urging them to come up with concrete results.

Before the talks began, Ukrainian President Volodymyr Zelensky said his country was prepared to declare neutrality, one of Russia’s key demands. However, one of his main negotiators, Foreign Minister Dmytro Kuleba, made clear he had instructions that “we do not trade people, land or sovereignty”.

Russian state news agency Ria Novosti released a picture showing Mr Abramovich talking to the Turkish president and Foreign Minister Mevlut Cavusoglu at the meeting.

He was also spotted in Turkish TV coverage listening to a translation wearing headphones, sitting alongside Mr Erdogan’s spokesman Ibrahim Kalin. They were not at the main table of the Russian and Ukrainian delegations.

The exact nature of Mr Abramovich’s role is unclear, although the Kremlin said he had played an early mediation role. His yacht Eclipse has been seen moored at the Turkish port of Marmaris in recent days.

The Ukrainian foreign minister told national TV hours before the talks that he had advised his colleagues attending negotiations with Russia not to eat or drink anything.