Twitter has suspended hundreds of accounts which it believes to be part of a covert Chinese government campaign designed to “undermine the legitimacy” of Hong Kong's protest movement.

The social network said it had “reliable evidence” that 936 accounts which had been tweeting about the protests were part of a “coordinated state-backed operation”.

Their purpose, it said, was to “sow political discord” in the territory and to “undermine the legitimacy and political positions” of the pro-democracy protesters who have brought one of the world's major financial centres to a standstill.

Facebook also said that it had removed seven pages linked to the Chinese government with about 15,500 followers between them, which had compared protesters to cockroaches and Isil terrorists.

The protests, now in their third month, are facing an intense crackdown by the Chinese government, which took over Hong Kong from the UK in 1997, as well as a propaganda blitz from state-run media.

“Covert, manipulative behaviors have no place on our service — they violate the fundamental principles on which our company is built,” said Twitter in a statement.

“As we have said before, it is clear that information operations and coordinated inauthentic behavior will not cease... we will continue to be vigilant, learning from this network and proactively enforcing our policies to serve the public conversation.”