By Donie O'Sullivan, CNN Business

(CNN) -- Every time President Donald Trump tweets, thousands of Twitter users reply. There are all shades of comments, from effusive praise to disdain and, of course, some garden variety trolling. The replies can be a good place for users to try to get the attention of the President, who has been known to retweet many who mention him, as well as the attention of his tens of millions of followers.

Now, researchers at the Institute for Strategic Dialogue (ISD), a London-based think tank, say they have found pro-Chinese Communist Party (CCP) accounts spamming the replies of the President and other US officials about Covid-19 on Twitter.

Accounts with usernames like @Dotard36639316, @alex75471129, and @susanblunt2020, all only set up in March of this year, tweeted at President Trump hundreds of times, often falsely claiming that America, not China, was the source of Covid-19. These accounts were among thousands identified by the researchers. Their report said the accounts were using Twitter to push talking points in favor of CCP, China's ruling party.

In response, Twitter questioned the report and said it has seen an uptick in use from real Chinese-speaking users since the outbreak of Covid-19. Although the government in Beijing has been shown to be running fake accounts on the social network, it's also very possible many of the accounts spamming the president with pro-CCP messaging are real CCP supporters and sympathizers.

The accounts' activity shows how the propaganda battle over who is responsible for the outbreak of Covid-19 is now playing out in the replies to tweets from lawmakers. The research also underscores how challenging it can be to determine who is behind what are often faceless accounts online — a government, a misinformation group for hire, a concerned citizen, or someone with a different motive.

These accounts, which sometimes tweeted in broken English, had almost no followers and were apparently more intent on getting the attention of Trump and his followers than building a mass audience. ISD said it identified the accounts by examining the followers of Chinese government officials.

An account's short life on Twitter — and more than 180 replies to President Trump

On April 3rd, the account @susanblunt2020 tweeted in response to President Trump: "It's very suspicious that there are so many cases in American (sic), only explanation is that America is the source."

Another tweet from the same account on March 27th read, "Why did not tell us the virus started in [September] in the US? Why your politicians still blaming China? Why your media still saying China needs to pay for your not taking actions."

In an apparent attempt to appear legitimate, the account @susanblunt2020 used a picture of an American blogger as its profile picture. The blogger, who CNN Business is not naming, said she did not know who was behind the account.

Of the 238 tweets @sunsanblunt2020 sent in its short life on Twitter, more than 180 of them directly mentioned President Trump's Twitter username, according to data gathered in ISD's analysis and seen by CNN Business.

Twitter suspended @Dotard36639316, @alex75471129, and @susanblunt2020 for breaking its rules on platform manipulation after CNN Business asked about them. The company would not say who was behind the accounts, if they were linked to each other, or where they were run from.

Attribution of who is really behind accounts is normally only possible to determine through access to non-public information, such as IP and email addresses — information normally only accessible to companies like Twitter and intelligence agencies. Twitter now publicly discloses a few times a year when it shuts down networks of accounts it determines are linked to nation-states.

ISD told CNN Business it handed over details of almost 10,000 accounts to Twitter in July and that Twitter suspended 3,000 of them. A Twitter spokesperson told CNN Business that after ISD reported the accounts to the company, the social network asked account holders to provide additional information, like a phone number, in an effort to prove the account is not suspicious or spam. The Twitter spokesperson said some of the accounts ISD flagged were suspended for not responding to Twitter's request.

While calling them "pro-Chinese Communist Party," ISD was careful not to claim the accounts they found were tied to the government in Beijing, but Twitter still said it had "strong concerns" about the methodology the group used to identify the approximately 10,000 accounts in the report. A Twitter spokesperson said ISD had flagged some real and legitimate users as suspicious in its research.

ISD said data it had on about 1,100 of the suspended accounts showed 767 of them had mentioned @realDonaldTrump.

The ISD released its findings Thursday in a joint report with the German Marshall Fund's Alliance for Securing Democracy.

CNN has asked the government in Beijing for comment on the report.

Tensions over identifying influence operations

Twitter's comments on ISD's findings highlight an ongoing tension between Silicon Valley companies and independent researchers. Academics, think tanks, journalists and others now regularly publish findings based on opensource information that point to coordinated influence campaigns, often involving hundreds or thousands of fake social media accounts.

Sometimes these outside findings feed into the work the social media platforms do in positively identifying such campaigns; other times these groups can be wrong.

Chloe Colliver, who leads the digital research unit at ISD, said her team was careful not to make a determination on who was behind the accounts, or indeed if the accounts were linked, but instead focused on the accounts' behavior.

"We hope this is part of a process where civic society and tech companies can constructively engage in order to confront the manipulation of tech platforms," she told CNN Business.

According to Twitter and Facebook, however, there is no question that China has been involved in covert online campaign especially over the past year — the type of operations involving trolls, bots, and fake accounts that Americans may associate more with Russia after its use of social media to interfere in the 2016 U.S. presidential election.

In June, Twitter shut down 170,000 accounts it linked to Beijing which pushed deceptive narratives around Covid-19 and other topics.

Renee DiResta, research manager at the Stanford Internet Observatory (SIO) who also analyzed the accounts taken down in June, said many of those that posted about Covid-19 throughout the spring had only been set up in late January.

"Narratives around Covid," the SIO wrote in its analysis, "praise China's response to the virus while tweets also use the pandemic to antagonize the U.S. and Hong Kong activists."

An ISD review of those accounts did not find a high amount of direct mentions of Trump's account.

Responding to Twitter's takedown in June, Hua Chunying, Chinese Foreign Ministry spokeswoman, said, "this is the perfect example of ideological prejudice, bias against China, blatant double standards, and the behavior to confuse right and wrong. What should be shut down is precisely the accounts that attack and smear China in an organized and coordinated manner."

But it is not just covert operations. Researchers at the German Marshall Fund's Alliance for Securing Democracy who track information operations online have noted an uptick in China's diplomatic corps use of Western social media platforms over the past year as Beijing faced intense scrutiny because of its handling of Covid-19 and also protests in Hong Kong.

A Chinese diplomat and Chinese Communist Party media promoted a false conspiracy theory that the US military brought the coronavirus to China. One US Army reservist who found herself at the center of the conspiracy theory and was falsely accused of starting the pandemic described to CNN Business in April how her life had been turned upside down.

"Some foreign media and social platforms are fraught with lies and rumors against China," Chunying said in June. "In the dark and ugly world of disinformation, it is necessary for some people, including Chinese diplomats, to speak in a truthful, objective and impartial manner, like striking a match in the dark night to bring some light. Anyone who is not playing deaf and dumb will be able to see the truth."

A blend of official spokespeople who apparently have no problem bending the truth, state-controlled media, and networks of covert social media accounts all help create a fog of misinformation that has become a reality of being online in 2020.