Some American intelligence officers are especially concerned about disinformation aimed at Europeans that pro-China actors appear to have helped spread. The messages stress the idea of disunity among European nations during the crisis and praise China’s “donation diplomacy,” American officials said. Left unmentioned are reports of Chinese companies delivering shoddy equipment and European leaders expressing skepticism over China’s handling of its outbreak.

Mr. Trump himself has shown little concern about China’s actions. He has consistently praised the handling of the pandemic by Chinese leaders — “Much respect!” he wrote on Twitter on March 27. Three days later, he dismissed worries over China’s use of disinformation when asked about it on Fox News.

“They do it and we do it and we call them different things,” he said. “Every country does it.”

Asked about the new accusations, the Chinese Foreign Ministry released a statement on Tuesday that said, “The relevant statements are complete nonsense and not worth refuting.” Zhao Lijian, a ministry spokesman, has separately rebutted persistent accusations by American officials that China has supplied bad information and exhibited a broader lack of transparency during the pandemic. “We urge the U.S. to stop political manipulation, get its own house in order and focus more on fighting the epidemic and boosting the economy,” Mr. Zhao said at a news conference on Friday.

An Information War

The United States and China are engaged in a titanic information war over the pandemic, one that has added a new dimension to their global rivalry.

President Trump and his aides are trying to put the spotlight on China as they face intense criticism over the federal government’s widespread failures in responding to the pandemic, which has killed more than 40,000 Americans. President Xi Jinping and the Chinese Communist Party are trying to shore up domestic and international support after earlier cover-ups that allowed the virus to spread.

As diplomatic tensions rose and Beijing scrambled to control the narrative, the Chinese government last month expelled American journalists for three U.S. news organizations, including The Times.

The extent to which the United States might be engaging in its own covert information warfare in China is not clear. While the C.I.A. in recent decades has tried to support pro-democracy opposition figures in some countries, Chinese counterintelligence officers eviscerated the agency’s network of informants in China about a decade ago, hurting its ability to conduct operations there.