The Sept. 9-10 summit had been seen as a venue for a possible meeting between Xi and Biden, who has confirmed his attendance in New Delhi, following months of efforts by the two powers to stabilize ties frayed by trade and geopolitical tensions.
"The G20 is the main forum for international economic cooperation and China has always placed great importance on and proactively taken part in such events," Chinese foreign ministry spokesperson Mao Ning told a press conference, when asked by a reporter why China's "leader" would not attend.
Mao declined to directly confirm that Li's attendance meant that Xi would not go, although she did not correct reporters who made that assertion. Reuters reported exclusively last month that Xi was likely to skip the meeting and send Li.
Li leading the delegation at the G20 meeting makes it all but certain that Xi will not be going since China would not have both its president and premier abroad at the same time, let alone at the same event.
Biden said on Sunday that he was disappointed Xi was not going to the summit but added that he was going to "get to see him." Biden did not elaborate.
Xi last met Biden on the sidelines of a G20 summit in Indonesia in November.
Germany, Europe's largest economy, also "regrets" Xi's decision not to attend, a spokesperson for its government said on Monday.
This will be the first time that a Chinese president has missed a leaders' summit since the first edition was held in 2008, though in 2020 and 2021, during the COVID-19 pandemic, Xi attended virtually.
Also absent from the New Delhi summit will be Russian President Vladimir Putin, following an International Criminal Court arrest warrant for him over alleged war crimes in Ukraine. Russia will be represented by its foreign minister.
The other G20 leaders attending include German Chancellor Olaf Scholz, French President Emmanuel Macron and Japanese Prime Minister Fumio Kishida.
'Setting his own agenda'
Wen-Ti Sung, political scientist at the Australian National University, pointed out that Xi had joined a meeting in South Africa last month of leaders of the BRICS group of major emerging economies.
"Xi's skipping the West-heavy club of G20 right after attending the BRICS summit may be a visual illustration of Xi's narrative of 'East is rising, and the West is falling', as well as showing solidarity with Russia's President Putin who is also not attending," Sung said.
The other venue where Xi and Biden could meet would be November's Asia-Pacific Economic Cooperation, APEC, summit in San Francisco.
Senior U.S. officials have traveled to China in recent months to strengthen communications amid concern that their friction could spiral out of control.
U.S. Commerce Secretary Gina Raimondo, the most recent official to have visited China, said the U.S. does not want to decouple from China.
Alfred Wu, associate professor at the Lee Kuan Yew School of Public Policy at the National University of Singapore, said Xi might be reluctant to travel abroad, given his focus on domestic issues.
"Xi Jinping is setting his own agenda where his top concern is national security and he has to stay in China and make foreign leaders visit him instead," Wu said.
"But if Xi skips APEC, that would be very substantial after all the preparations made for it by the U.S. side, and it would reflect even more badly on China's future and its international standing, since it still needs foreign investment."
Xi's absence from the G20 gathering could also be seen as a snub of host India, say some analysts, suggesting it could be a signal that China is unwilling to confer influence on its southern neighbor that boasts one of the fastest growing major economies while China's slows.
Ties between India and China have been also troubled for more than three years after soldiers from both sides clashed on their disputed Himalayan frontier in June 2020, resulting in 24 deaths.