Billionaire Roman Abramovich is not an official member of the Russian team negotiating with Ukraine, but is present at the talks in Turkey to "enable certain contacts" between the two sides, the Kremlin said on Tuesday.

Abramovich who is sanctioned by the West over Moscow's invasion of Ukraine due to his ties with President Vladimir Putin, was present on Tuesday at the first direct peace talks in more than two weeks in Istanbul.

"Roman Abramovich is involved in enabling certain contacts between the Russian and Ukrainian sides," Kremlin spokesperson Dmitry Peskov told reporters in a conference call.

"He is not an official member of the delegation... but nevertheless he is also present today in Istanbul from our side," he said.

"In order to carry out contacts between the two sides, you need to get approval from both sides, and in the case of Abramovich, this approval is there from both sides," he added.

The Kremlin, which has said Abramovich also played an early role in peace talks, dismissed reports that he had been poisoned, saying they were untrue and part of an "information war."

According to the Wall Street Journal and the investigative outlet Bellingcat, which cited people familiar with the matter, Abramovich and Ukrainian peace negotiators suffered symptoms of suspected poisoning earlier this month after a meeting in Kyiv.

Ukrainian officials have also poured cold water on the reports.

Peskov told reporters that it would become clear either on Tuesday or Wednesday if the peace talks were promising.