MENLO PARK, Calif. (AP) — A disinformation network with ties to China used hundreds of fake social media accounts — including one belonging to a fictitious Swiss biologist — to spread an unfounded claim that the U.S. pressured scientists to blame China for the coronavirus, Facebook said Wednesday.

The company based in Menlo Park, California, did not directly attribute the network to the Chinese government. But it noted employees of Chinese state-run companies, and the country's state-run media, worked to amplify the misleading claims, which were soon the subject of news headlines in China.

"In effect it worked like an online hall of mirrors, endlessly reflecting the original fake persona and its anti-US disinformation," according to Ben Nimmo, who leads investigations into disinformation at Meta, the parent company of Facebook and Instagram.

The operation began in July, when a Facebook account was created in the name of Wilson Edwards, a self-professed Swiss biologist. That same day, the account user claimed, without evidence, that U.S. officials were using "enormous pressure and even intimidation" to get scientists to back calls for renewed investigations into the origin of the virus.

Within hours, hundreds of other accounts — some of which were created only that day — began liking, posting or linking to the post. Many of the accounts were later found to be fake, with some of the users posing as westerners and others using likely fabricated profile photos. Facebook said it found links between the accounts and a tech firm based in Chengdu, China, as well as to overseas employees of Chinese infrastructure companies.

Within a week of the initial post, large media outlets in China were reporting on the claims of U.S. intimidation as if they had been made by a real scientist.

The operation was exposed when Swiss authorities announced in August that they had no record of any biologist with Edwards' name. "If you exist, we would like to meet you!" the Swiss embassy in Beijing tweeted.

China's Ministry of Foreign Affairs has said in the past that the country's government does not employ trickery on social media. Efforts to contact the companies cited in the report weren't immediately successful on Wednesday.

In all, Meta removed about 600 accounts on Facebook and Instagram that were linked to the network, Nimmo told reporters on a call Wednesday that touched on the company's response to several disinformation networks around the world.

Facebook uncovered fake accounts affiliated with the network that had also waded into U.S. politics last year, with some posting memes that both attacked and supported ex-President Donald Trump. One post on Instagram called him "the worst president ever!" The group behind the effort also created accounts on Twitter, which has since suspended the account supposedly created by Edwards.

Nimmo said the network was easily spotted by its clumsy tactics. Several of the fake accounts sent out identical posts at similar times — a clear indication of coordination. Another person apparently working for the network posted instructions for reposting the claim in what Facebook determined was likely a sloppy mistake.

China's disinformation networks have consistently been haphazard, said Bret Schafer, who heads the information manipulation team at the Alliance for Securing Democracy, a non-partisan think tank in Washington.

The network unearthed by Facebook show that the Chinese are still working on their influence campaign strategy, unlike Russia, which has spent decades crafting disinformation campaigns that target unwitting Americans online and go undetected for years.

"It didn't take long for this to be unraveled," Schafer said. "The Chinese are still a bit sloppier with what they do. I can't imagine the Russians doing something like this, where they just create a persona out of thin air."