WASHINGTON — President Joe Biden is sending his national security adviser for talks with a senior Chinese official in Rome on Monday as concerns grow that China is amplifying Russian disinformation in the Ukraine war and may help Russia evade punishment from economic sanctions.

The talks between National Security Adviser Jake Sullivan and a senior Chinese foreign policy adviser, Yang Jiechi, will center on “efforts to manage the competition between our two countries and discuss the impact of Russia’s war against Ukraine on regional and global security,” a representative of the White House national security council, Emily Horne, said.

The White House has accused Beijing of spreading false Russian claims that Ukraine was running chemical and biological weapons labs with U.S. support. U.S. officials said China was attempting to provide cover for a potential biological or chemical weapons attack on Ukrainians by the Russian military.

Mr. Sullivan said on NBC’s “Meet the Press” on Sunday that when Russia starts accusing other countries of preparing to launch biological or chemical attacks, “it’s a good tell that they may be on the cusp of doing it themselves.”

He also said China and other countries should not try to help Russia work around the sanctions and the U.S. has made it clear that other countries should not bail out the Russian economy. “We will ensure that neither China nor anyone else can compensate Russia for these losses,” Mr. Sullivan said.

The striking accusations about Russian disinformation and Chinese complicity came after a Russian foreign ministry spokeswoman, Maria Zakharova, alleged with no evidence that the U.S. was financing Ukrainian chemical and biological weapons labs.

The Russian claim was echoed by the Chinese foreign ministry spokesman, Zhao Lijian, who claimed there were 26 bio-labs and related facilities in “which the U.S. Department of Defense has absolute control.” The United Nations has said it has received no information backing up such accusations.

The White House press secretary, Jen Psaki, last week called the claims “preposterous.”

“Now that Russia has made these false claims, and China has seemingly endorsed this propaganda, we should all be on the lookout for Russia to possibly use chemical or biological weapons in Ukraine, or to create a false flag operation using them,” Ms. Psaki tweeted Wednesday night. “It’s a clear pattern.”

The international community for years has assessed that Russia has used chemical weapons in carrying out assassination attempts against detractors of President Putin such as a major politicial opposition leader, Alexei Navalny, and a former spy, Sergei Skripal. Russia also supports the Assad government in Syria, which has used chemical weapons against its people in a decade-long civil war.

Testifying before the Senate Intelligence Committee on Thursday, the CIA director, William Burns, also noted grave concern that Russia might be laying the groundwork for a chemical or biological attack of its own, which it would then blame on the U.S. or Ukraine in a false flag operation.

“This is something, as all of you know very well, is very much a part of Russia’s playbook,” he said. “They’ve used these weapons against their own citizens, they’ve at least encouraged the use in Syria and elsewhere, so it’s something we take very seriously.”

China has been one of few countries to avoid criticizing the Russians for its invasion of Ukraine. China’s leader, Xi Jinping, hosted Mr. Putin for the opening of the Winter Olympics in Beijing, just weeks before Russia launched the February 24 invasion.

During Mr. Putin’s visit to China last month, the two leaders issued a 5,000-word statement declaring “no limits” in the friendship between the two countries.

The Chinese abstained on U.N. votes censuring Russia and has criticized economic sanctions against Moscow. It has expressed its support for peace talks and offered its services as a mediator, despite questions about its neutrality and scant experience mediating international conflict.

Chinese officials have also said Washington shouldn’t be able to complain about Russia’s actions because the U.S. invaded Iraq under false pretenses. The U.S. claimed to have evidence Saddam Hussein was stockpiling weapons of mass destruction though none was ever found.

For Russia, China could be a crucial economic partner in mitigating the severe sanctions levied by America, Britain, the 27-national European Union, and other countries, though there are questions how far Beijing will go to alienate the alliance and put its own economy at risk.

The Biden administration is looking to impress on China that any efforts to ease sanctions for Russia could have ramifications for its relations with the United States and Western allies.

Messrs. Sullivan and Yang last met for face-to-face talks in Switzerland, where Mr. Sullivan raised the Biden administration’s concerns about China’s military provocations against Taiwan, human rights abuses against ethnic minorities, and efforts to squelch pro-democracy advocates in Hong Kong.

That meeting set the stage for a three-hour virtual meeting in November between President Biden and Mr. Xi.

Mr. Sullivan is also to meet Luigi Mattiolo, diplomatic adviser to the Italian prime Minister, Mario Draghi, while in Rome.

By AAMER MADHANI and JOSH BOAK