Facebook and Twitter said Monday that they had removed a sweeping network of troll accounts linked to China that aimed to fuel political discord in Hong Kong, where protesters have taken to the streets in the past several months.

Twitter said it pulled down 936 troll accounts, many of which pushed conspiracy theories about the protest groups, according to examples shared by the company. Protesters began rallying in March against an extradition bill that organizers feared would eventually place Hong Kong under China’s jurisdiction.

Since then, the protests have expanded but also been the scene of some violent clashes with police. On Sunday, tens of thousands of protestors stood in heavy rain in a show of the movement’s ongoing enthusiasm. The large turnout suggested the movement retains widespread support as it continues to push for greater freedoms amid Beijing's growing influence over the former British colony.

One conspiratorial post in English highlighted by Twitter’s public safety team reads: “Are these people who smashed the Legco (Legislative Council of Hong Kong) crazy or taking benefits from the bad guys?”

Twitter said the company has “reliable evidence to support that this is a coordinated state-backed operation.”

Many of the English-language accounts purported to be from various municipalities in the U.S., including major cities such as New York City and towns like Berrien Springs, Michigan. The accounts gained followers by tweeting about noncontroversial cultural events, like the NBC show “This Is Us.” Building up follower bases to eventually be deployed during a disinformation campaign is a common tactic of social media misinformation efforts.

Other accounts successfully posed as Hong Kong news accounts, like @HKPoliticalNew, which was active on Twitter since 2015 and on Facebook since March 2018.

Shortly after Twitter announced its Chinese troll-farm takedown, Facebook announced it had removed 16 Facebook pages, accounts or groups associated with the troll farm. The accounts had accrued about 15,500 followers.

“Although the people behind this activity attempted to conceal their identities, our investigation found links to individuals associated with the Chinese government,” a Facebook press release stated.

Twitter faced scrutiny earlier on Monday when it was reported that the company had accepted ad money from Chinese state-sponsored media, whose ads attacked and sought to discredit protesters in Hong Kong.

A spokesperson for Twitter said the company would no longer accept ad money from foreign, state-backed media. The accounts will still be allowed to use the platform, but not purchase advertising space in users’ feeds.

The spokesperson said they would remove all foreign state media advertisers from their advertising platform to “protect the health of the public conversation” on the social media network. Twitter had already banned Russian state media organizations RT and Sputnik in 2017.

Last week, some Twitter users flagged what they believed to be Chinese government accounts responding to a controversy about the upcoming live-action Disney movie “Mulan.”

The movie’s star, Crystal Liu Yifei, posted a message of support for Hong Kong police on the Chinese social media site Weibo, which is similar to Twitter. People sympathetic to the protesters then pushed a #BoycottMulan hashtag.

Some accounts included in Twitter’s Monday takedown began responding with pro-China talking points to those sympathetic to protesters who were tweeting the #BoycottMulan hashtag.

“You should come to Hong Kong to see the truth, not be misled by unscrupulous Western media and politicians,” reads a reply tweet from the account @shu_zhiyuan, which has since been banned by Twitter.