On Feb. 27, an article claiming that the United States was behind the bombing of the Nord Stream underwater pipelines in the Baltic Sea was published on the Substack and Blogspot blogging platforms.

Within 24 hours, the article — and other versions of it — had been posted to more websites, including Reddit, Medium, Tumblr, Facebook and YouTube. Translations of the article in Greek, German, Russian, Italian and Turkish also began appearing online.

The posts were part of a Chinese influence campaign that stands out as the largest such operation to date, researchers at Meta said in a report on Tuesday. The effort, which the company said had started with Chinese law enforcement and was discovered in 2019, was aimed at advancing China’s interests and discrediting its adversaries, such as the United States, Meta said.

In total, 7,704 Facebook accounts, 954 Facebook pages, 15 Facebook groups and 15 Instagram accounts tied to the Chinese campaign were removed by Meta, which owns Facebook, Instagram and WhatsApp. Hundreds of other accounts on TikTok, X, LiveJournal and Blogspot also participated in the campaign, which researchers named Spamouflage, for the frequent posting of spamlike messages, according to Meta’s report.

“This is the biggest single takedown of a single network we have ever conducted,” said Ben Nimmo, who heads Meta’s security team that looks at global threats. “When you put it together with all the activity we took down across the internet, we concluded it is the largest covert campaign that we know of today.”

The Chinese campaign struggled to reach people and attract attention, Mr. Nimmo said. Some posts were riddled with spelling errors and poor grammar, while others were incongruent, such as random links under Quora articles that people could see had nothing to do with the subject being discussed.

Yet the operation is being disclosed at a delicate time in the relationship between the United States and China. Commerce Secretary Gina Raimondo is in China this week to talk with government officials and Chinese business leaders about trade relations. She is the fourth senior U.S. official to travel to China in less than three months.

The influence operation was the seventh from China that Meta has removed in the last six years. Four of them were found in the last year, said the company, which published details of the new operation as part of a quarterly security report.

The effort appeared to “learn and mimic” Russian-style influence operations, Meta said. It also appeared aimed at a broad audience. At times, posts were in Chinese on websites such as the Chinese financial forum Nanyangmoney. At other times, posts were in Russian, German, French, Korean, Thai and Welsh on sites such as Facebook and Instagram, which are banned in China.

Chinese law enforcement appeared to work on the campaign from offices spread throughout the country, Meta said. Each office appeared to work in shifts, with activity in the midmorning and early afternoon, and breaks for lunch and dinner, the report said.

The accounts frequently posted identical messages on different social media platforms, in a timed effort to spread pro-China messaging online. The network was “wide and noisy,” Mr. Nimmo said, but struggled to reach people partly because “it was the same comment many times a day.”

“It was as if they copied them from a numbered list and forgot to proofread them before they posted,” he added.

While Meta has removed the campaign from Facebook and Instagram, many of the operation’s accounts on platforms like X, Reddit and TikTok remain online, according to a review by The New York Times.

The effort was discovered in 2019 by Mr. Nimmo and other researchers at Graphika, a company that studies social media. Meta said that it had removed elements of the operation in recent years, but that the campaign had kept returning with new accounts and tactics.

The operation initially focused on discrediting the 2019 pro-democracy protests in Hong Kong. In February 2020, the effort shifted to the outbreak of Covid-19, deflecting assertions that China was the origin of the virus and focusing blame on the United States.

In one instance, the operation published a 66-page research paper falsely claiming that Covid had started in the United States. It appeared on the website Zenodo, an online repository for researchers and academics to upload papers and data sets.

YouTube and Vimeo videos then promoted the research paper, along with posts on blogging platforms including LiveJournal, Tumblr and Medium that argued that the United States had hidden Covid’s true origins. Links to those posts were then published on Facebook and other social media sites, though many of the posts were not widely read.

In June 2020, the network began posting English-language videos on YouTube and TikTok that highlighted racial disparities in the United States, in an apparent effort to inflame divisions. Some of those videos went viral.

Meta also included links in its report to TikTok accounts that it said had been part of the Chinese operation. One of the most popular videos, which The Times viewed, showed a woman arguing in Chinese that life in Xinjiang, a far northwestern region of China, was peaceful. China has been under international scrutiny for carrying out repressive policies against Uyghurs and other predominantly Muslim ethnic minorities in the region.

The TikTok video was viewed more than 7,000 times.