U.S. Secretary of State Antony Blinken and Russian Foreign Minister Sergei Lavrov had a brief encounter on the sidelines of the meeting during which Blinken urged Russia to reverse its decision on the New START nuclear treaty, a senior U.S. official said.
Blinken also told Lavrov that Washington was prepared to support Ukraine to defend itself for as long as it takes, the official said. The two spoke for less than 10 minutes, they said.
The Russian foreign ministry said Lavrov and Blinken spoke "on the move" but did not hold negotiations or a meeting, Russian news agencies reported.
News of the exchange came at the end of the day-long G20 meeting which, as expected, was overshadowed by the Ukraine war.
The United States and its European allies urged the Group of 20 (G20) nations to keep up pressure on Moscow to end the conflict, now in its second year.
Russia hit back, accusing the West of turning work on the G20 agenda into a "farce" and said Western delegations wanted to shift responsibility for their economic failures onto Moscow.
"We must continue to call on Russia to end its war of aggression and withdraw from Ukraine for the sake of international peace and economic stability," Blinken said in remarks released after his address at the closed-door meeting.
"Unfortunately, this meeting has again been marred by Russia’s unprovoked and unjustified war against Ukraine," Blinken said.
He was backed by his counterparts from Germany, France and the Netherlands.
"Unfortunately, one G20 member prevents all the other 19 from focusing all their efforts on these issues the G20 was created for," German Foreign Minister Annalena Baerbock told the meeting, according to the German delegation.
"I ask you, Mr Lavrov, to return to full implementation of New START (nuclear arms treaty) and to resume dialogue with the U.S. Because, as China rightly pointed out in its 12-points-plan, the threat of nuclear weapons should be opposed," she said.
President Vladimir Putin last week announced Russia's decision to suspend participation in the latest START treaty, after accusing the West - without providing evidence - of being directly involved in attempts to strike its strategic air bases.
Russian Deputy Foreign Minister Sergei Ryabkov, speaking at a U.N. conference in Geneva, said the United States had attempted "to probe the security of Russian strategic facilities declared under the New START Treaty by assisting the Kyiv regime in conducting armed attacks against them".
French Foreign Minister Catherine Colonna said the war in Ukraine had hurt "almost every country on the planet, in terms of food, energy, inflation".
"The G20 must respond firmly, like it did at the Bali Summit. The message at Bali was clear, as G20, we need to deliver solutions that protect the most vulnerable, instead of leaving them to suffer from Russia's war," Colonna said, referring to the November meeting of heads of state and governments in Indonesia.
Dutch Foreign Minister Wopke Hoekstra told CNBC that Russia was solely responsible for the war and must continue to be sanctioned.
'Farce'
Russia's Lavrov, however, blamed the West for the global political and economic crises.
"A number of Western delegations turned the work on the G20 agenda into a farce, wanting to shift the responsibility for their failures in the economy to the Russian Federation," Lavrov said, according to a Russian statement.
"The West creates obstacles for the export of agricultural products of the Russian Federation, no matter how the representatives of the EU convince the contrary," he said.
Lavrov also accused the West of "shamelessly burying" the Black Sea grain initiative that facilitates the export of Ukraine's agricultural products from its southern ports, the RIA Novosti news agency reported.
In an inaugural address, Indian Prime Minister Narendra Modi called on the foreign ministers to find common ground on global issues.
"You are meeting at a time of deep global divisions," Modi said in a video message. "We should not allow issues that we cannot resolve together to come in the way of those we can."
India, which holds the presidency of the bloc this year, has declined to blame Russia for the war and has sought a diplomatic solution while boosting its purchases of Russian oil.
The G20 is an economic grouping that includes the wealthy G7 nations as well as Russia, China, India, Brazil, Australia and Saudi Arabia, among other nations.