(Reuters) - Twitter Inc and Facebook Inc said on Monday they had dismantled a state-backed social media campaign originating in mainland China that sought to undermine protests in Hong Kong.

FILE PHOTO: A 3D-printed logo for Twitter is seen in this picture illustration made in Zenica, Bosnia and Herzegovina on January 26, 2016. REUTERS/Dado Ruvic/Illustration/File Photo

Twitter said it suspended 936 accounts and the operations appeared to be a coordinated state-backed effort originating in China. It said these accounts were just the most active portions of this campaign and that a “larger, spammy network” of approximately 200,000 accounts had been proactively suspended before they were substantially active.

Facebook said it had removed accounts and pages from a small network after a tip from Twitter. It said that its investigation found links to individuals associated with the Chinese government.

The Hong Kong protests, which have presented one of the biggest challenges for Chinese President Xi Jinping since he came to power in 2012, began in June as opposition to a now-suspended bill that would allow suspects to be extradited to mainland China for trial in Communist Party-controlled courts. They have since swelled into wider calls for democracy.

Social media companies globally are under pressure to stem illicit political influence campaigns online, especially ahead of the U.S. election in November 2020. A 22-month U.S. investigation concluded Russia interfered in a “sweeping and systematic fashion” in the 2016 U.S. election to help Donald Trump win the presidency.

The Chinese embassy in Washington and the U.S. State Department did not respond to requests for comment.

Twitter in a blog post said the accounts undermined the legitimacy and political positions of the protest movement in Hong Kong. (bit.ly/30kl9Jk)

Examples of posts provided by Twitter included a tweet from a user with photos of protesters storming Hong Kong’s Legislative Council building, which asked: “Are these people who smashed the Legco crazy or taking benefits from the bad guys? It’s a complete violent behavior, we don’t want you radical people in Hong Kong. Just get out of here!”

In examples provided by Facebook, posts described the protesters as cockroaches who “refused to show their faces.”

Facebook’s head of cybersecurity policy Nathaniel Gleicher told reporters that the bulk of the Facebook accounts were created in 2018.

Both Twitter and Facebook are blocked in mainland China by the government but available in Hong Kong.

TWITTER CHANGES AD POLICY

Twitter and Facebook have come under fire from users over showing ads from state-controlled media that criticized the Hong Kong protesters.

In response, Twitter said Monday it would no longer accept advertising from state-controlled news media. Twitter told Reuters the advertising change was not related to the suspended accounts. (bit.ly/2Za5Pxn)

In the past week, China’s official Xinhua news agency and state broadcaster China Global Television Network (CGTN) paid to promote videos that portrayed the protests as violent and said Hong Kong citizens wanted the demonstrations to end, according to Twitter’s Ads Transparency Center.

Twitter said it did not have data on how much revenue it generates from state-controlled media advertising.

Many countries including the United States do not have clear standards on state media’s purchase of online advertising.

Total digital ad spending in Hong Kong will grow 11% to reach $786.1 million in 2019, according to projections by U.S. digital market data analyst eMarketer.

Alphabet Inc’s YouTube video service told Reuters in June that state-owned media companies maintained the same privileges as any other user, including the ability to run ads in accordance with its rules. YouTube did not immediately respond to a request for comment on Monday on whether it had detected inauthentic content related to protests in Hong Kong.

In a tweet on Sunday, China’s influential state-run tabloid, The Global Times, hailed the response of Chinese “netizens” to the protests, saying: “Chinese netizens’ power! Amid escalating protests in Hong Kong, Chinese netizens on Saturday swept Facebook and Instagram to denounce secessionist posts and show support for Hong Kong police.”

About 98% of social network users in Hong Kong, or 4.7 million people, will log into Facebook at least once a month in 2019, according to eMarketer projections, while 9.4% of social network users will use Twitter.

Shares of Facebook rose 1.3% and Twitter rose 2.8%.