Russian Foreign Minister Sergey Lavrov visited and later left a Bali hospital ahead of the Group of 20 summit being held on the island, Indonesian authorities said.
Russia denied on Monday that he had been hospitalised.
Russia's top diplomat arrived on the resort island the Sunday evening to take part in the meeting of the world's leading economies, which begins onTuesday.
Bali Governor I Wayan Koster said Lavrov was taken to Sanglah Hospital, the island's biggest, "for a health checkup."
"He left the hospital after a brief checkup and his health is in good condition," the governor said on Monday.
Four Indonesian government and medical officials earlier told The Associated Press that Lavrov was treated at the hospital in the provincial capital, Denpasar.
All of those officials declined to be identified as they were not authorised to discuss the matter publicly. Two of the people said Lavrov had sought treatment for a heart condition, with one later saying he'd returned to his hotel.
The hospital did not immediately comment.
Russian Foreign Ministry spokesperson Maria Zakharova denied that Lavrov had been hospitalised, calling it "the highest level of fakes." She did not address whether he had received medical treatment.
She posted a video of Lavrov, looking healthy in a T-shirt and shorts, in which he was asked to comment on the report.
"They've been writing about our president for 10 years that he's fallen ill. It's a game that is not new in politics," Lavrov says in the video.
Russia's state news agency Tass separately cited Lavrov as saying, "I'm in the hotel, reading materials for the summit tomorrow."
Asked about Lavrov's situation, UN Secretary General Antonio Guterres said he "did not know about what happened to Minister Lavrov. I wish him the best possible recovery and hope that tomorrow it will be possible to meet."
Lavrov is the highest-ranking Russian official at the G-20 meeting, which US President Joe Biden, China's Xi Jinping and other leaders are attending.
Russian President Vladimir Putin's attendance at the G-20 had been uncertain until last week, when officials confirmed he would not come and that Russia would be represented by Lavrov instead.
Fallout from Russia's invasion of Ukraine is expected to be among the issues discussed at the two-day G-20 meeting, which brings together officials from countries representing more than 80 per cent of the world's economic output.
Biden and Xi were meeting separately ahead of the summit in their first in-person talks since the US president took office.