Twitter said it has suspended more than 200,000 accounts involved in coordinated inauthentic behaviour including 936 accounts originating from within the People's Republic of China (PRC).
"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," Twitter said in a blog post late Monday.
The company identified large clusters of accounts behaving in a coordinated manner to amplify messages related to the Hong Kong protests.
"As Twitter is blocked in China, many of these accounts accessed Twitter using VPNs. However, some accounts accessed Twitter from specific unblocked IP addresses originating in mainland China," the micro-blogging platform added.
The accounts were suspended for a range of violations of Twitter's platform manipulation policies like spam, coordinated activity, fake accounts, attributed activity and violative content.
The micro-blogging platform said it will also ban ads from China-backed media companies, for which it has already faced the flak from users.
Facebook said it has also removed seven Pages, three Groups and five accounts originated in China and involved in posting fake news pertaining to the ongoing protests in Hong Kong.
The individuals behind this campaign engaged in a number of deceptive tactics, including the use of fake accounts, "some of which had been already disabled" to manage Pages posing as news organisations, post in Groups, disseminate their content, and also drive people to off-platform news sites.
"About 15,500 accounts followed one or more of these Pages and about 2,200 accounts joined at least one of these Groups,a Nathaniel Gleicher, Head of Cybersecurity Policy at Facebook, said in a blog post.
"Although the people behind this activity attempted to conceal their identities, our investigation found links to individuals associated with the Chinese government," he added.
Based on a tip shared by Twitter about activity they found on their platform, Facebook conducted an internal investigation into suspected coordinated inauthentic behaviour in the region and identified the malicious accounts.
Since June, Hong Kong has been rocked by a wave of protests because of the extradition bill, which would have enabled fugitives to be extradited from Hong Kong to mainland China.
A mass rally in Hong Kong on Sunday, widely deemed the most important so far this month, attracted tens of thousands of people as the crisis entered the 11th consecutive weekend of anti-government protests.
The recent wave of anti-government protests has prompted widespread criticism of the police for their alleged brutality against protesters.
( With inputs from IANS )