Russia’s foreign minister Sergey Lavrov has been taken to hospital after arriving in Bali for the G20 summit.
Two sources told the Associated Press that Lavrov, 72, was suffering from a heart condition.
The Indonesian government and medical officials said he was being treated on the resort island.
The Kremlin is yet to comment.
Russian President Vladimir Putin decided to skip the summit, which would have seen him come face-to-face with US President Joe Biden for the first time since the invasion of Ukraine.
The G20 summit opens on Tuesday and comes with food and fuel prices spiking worldwide, Ukraine mired in conflict and the renewed threat of nuclear war.
Officially, neither the war in Ukraine, nor Putin’s dark threats to use nuclear weapons are on the summit agenda, but the conflict will dominate discussions.
Soaring energy and food prices have hit richer and poorer G20 members alike — and both are directly fuelled by Putin’s war.
On Monday, US Treasury Secretary Janet Yellen said an end to the conflict was “a moral imperative and the single best thing we can do for the global economy”.
Russia will also be under pressure to extend a deal allowing Ukrainian grain shipments through the Black Sea when the agreement expires on November 19.
British Prime Minister Rishi Sunak will urge the agreement be renewed and call for “a G20-wide commitment never to weaponise food production and distribution”, Downing Street said.
At a minimum, Biden and his allies would also like to see the G20 make it clear to Putin that nuclear war is unacceptable.
But even a clear statement on this issue from the grouping is likely to be blocked by a mixture of Russian opposition and Chinese unwillingness to break ranks with its ally in Moscow or give Washington a win.
The G20 has always been more comfortable discussing finance and economics than security and Moscow would like it to stay that way.
“We categorically reject the politicisation of the G20,” the Russian foreign ministry said Sunday, offering a taste of what leaders might hear from the famously unbending Lavrov.
G20 ministerial meetings leading to the summit have failed to agree a final joint communique and Indonesian officials said Monday it remained a “work in progress” and a “main goal” for the summit.
“Honestly, I think the global situation has never been this complex,” Indonesian government minister Luhut Binsar Pandjaitan said Sunday.
“If eventually (the G20) leaders do not produce a communique, that’s that, it’s OK.”
More to come.