Russian foreign minister Sergey Lavrov was rushed to hospital after arriving in Bali for the G20 summit, sources claim.
However, Lavrov's spokeswoman denied the reports and shared a video of Vladimir Putin's right-hand man describing the claims as a "political game".
Earlier this morning, Indonesian officials told the Associated Press that the Russian diplomat was being treated for a heart condition on the island.
He was taken to Sanglah Hospital in the provincial capital Denpasar, it was claimed.
The Governor of Bali has since confirmed that Lavrov has left hospital.
Lavrov is the highest-ranking Russian official attending the G20 summit, which begins on Tuesday.
It comes after Putin chose to stay away from the meeting.
In a video shared by Lavrov's spokeswoman Maria Zakharova, she asked the Russian foreign minister: “Sergei Viktorovich [Lavrov], I am so awfully sorry - everyone is reporting you are hospitalised….?
In the clip, he responds: “So….they’ve been writing about our President [Vladimir Putin] being sick for the last 10 years.
“This is a game, and not a new game in politics.”
Lavrov did not specifically deny having visited a hospital on arrival and was not asked about the Governor of Bali's statement.
Downing Street suggested no meeting is planned between the UK and Lavrov at the G20 summit.
No10 was also unable to say whether Britain knew the Russian foreign minister was sick or not.
“I’ve seen those reports, I don’t have any information I’m afraid,” a spokeswoman said.
Britain's PM Rishi Sunak pledged to call out the Russian despot's warmongering at the summit.
“We will not shy away from any opportunity to make our position loud and clear,” the PM’s spokesman said.
Mr Sunak will call on Moscow to allow grain shipments out of Ukraine to continue as it threatens to stop them from this Saturday.
The PM will also urge fellow world leaders to maintain support for Volodymyr Zelensky. “[He] is emphatic that [our] support will not fade or alter and that we are in this for the long haul,” his spokesman said.
The leaders of the G20, which is made up of 19 nations and the EU, first met in 2008 in the wake of the financial crisis.
Meanwhile, Chinese President Xi Jinping has issued a warning to Russia not to use nuclear weapons in its war on Ukraine.
In recent months the Russian army has failed to make progress in its invasion of its neighbour and has been pushed back in parts of the east and south.
At the same time Putin has stated that he would be prepared to use nuclear weapons to protect Russian territory - which could include areas of Ukraine that the invading forces have annexed.
Putin said Russia would employ "all means" to defend its occupied territories in Ukraine, adding that he was "not bluffing".
But in a statement reported by Chinese state broadcaster CCTV, Xi Jinping said the international community should “jointly oppose the use of, or threats to use, nuclear weapons".
He further added that the world should "advocate that nuclear weapons cannot be used, a nuclear war cannot be waged, in order to prevent a nuclear crisis".
German Chancellor Olaf Scholz openly urged China's leader to use China's ties with Russia to de-escalate global nuclear tensions.
“President Xi and I agree that nuclear threats are irresponsible and highly dangerous," Scholz said following the pair's meeting.
"By using nuclear weapons, Russia would cross a line that the international community has drawn together."
At a later press conference, Scholz said he told Xi that “it’s important for China to exert its influence on Russia”.
