Google on Thursday said it disabled a series of YouTube channels that appeared to be part of a coordinated influence campaign against pro-democracy protests in Hong Kong.

Hong Kong, a semi-autonomous southern Chinese city and one of the world's most important financial hubs, is in the grip of an unprecedented political crisis that has seen millions of people take to the streets demanding greater freedoms.

Google disabled 210 YouTube channels that it found behaved in a coordinated manner while uploading videos related to the Hong Kong protests, according to Shane Huntley of the company's security threat analysis group.

"This discovery was consistent with recent observations and actions related to China announced by Facebook and Twitter," Huntley said in an online post.

The video removals come just days after Twitter said it had suspended more than 200,000 accounts it linked to a Chinese government influence campaign against the protests. Facebook also said it had suspended accounts and removed pages after being notified by Twitter.

Google, which owns YouTube, did not explicitly implicate the Chinese government but said the videos were related to the similar disclosures from Facebook and Twitter.

Facebook said some of the posts from accounts it banned compared the protesters in Hong Kong with Daesh militants, branded them "cockroaches" and alleged they planned to kill people using slingshots.

However, Twitter and Facebook are banned in China, part of the government's so-called "Great Firewall" of censorship.

Because of the bans, many of the fake accounts were accessed using "virtual private networks" that give a deceptive picture of the user's location, Twitter said.

Facebook said it had acted on a tip from Twitter, removing seven pages, three groups and five Facebook accounts that had about 15,500 followers.