Twitter and Facebook announced on Monday the suspension of Chinese accounts that they said spread disinformation about the Hong Kong pro-democracy protesters.

In a blog post, Twitter said it disabled 936 accounts involved in a “coordinated state-backed operation” to undermine the anti-extradition bill protests, now in their 11th week.

“We are disclosing a significant state-backed information operation focused on the situation in Hong Kong, specifically the protest movement and their calls for political change,” the social media site said.

“Overall, these accounts were deliberately and specifically attempting to sow political discord in Hong Kong, including undermining the legitimacy and political positions of the protest movement on the ground. Based on our intensive investigations, we have reliable evidence to support that this is a coordinated state-backed operation.”

Twitter said the 936 suspended accounts were the most active, but the disinformation campaign was comprised of a far larger contingent of nearly 200,000 accounts that were “proactively suspended before they were substantially active on the service.”

The social media site tipped off Facebook, which then conducted its own investigation that found a number of its accounts engaging in similar behavior.

“The individuals behind this campaign engaged in a number of deceptive tactics, including the use of fake accounts … to manage Pages posing as news organizations, post in Groups, disseminate their content, and also drive people to off-platform news sites,” Facebook said.

It removed seven pages, three groups and five accounts as a result of its probe.

“Although the people behind this activity attempted to conceal their identities, our investigation found links to individuals associated with the Chinese government,” the site said.

The Facebook pages drew about 15,500 followers and roughly 2,200 accounts joined one of the groups.