Twitter said Thursday that it removed more than 170,000 accounts tied to a Chinese influence operation that spread misinformation favorable to the Beijing regime about Hong Kong and coronavirus.

The company suspended 23,750 accounts that were part of a “highly engaged core network,” as well as a larger group of around 150,000 “amplifier” accounts designed to boost core account content, it said. This network was posting mostly in Chinese to “spread geopolitical narratives favorable to the Communist Party of China (CCP),” while also pushing misinformation about politics in Hong Kong.

Researchers said the accounts also posted about Taiwan and the exiled Chinese billionaire Guo Wengui, who is an outspoken critic of Beijing.

Stanford Internet Observatory (SIO) researcher Renee DiResta said that many accounts posting about coronavirus were set up in late January. They became more active as the outbreak began to spread beyond China’s borders. In an analysis, the SIO said that common narratives “praise[d] China’s response to the virus while… also us[ing] the pandemic to antagonize the U.S. and Hong Kong activists.”

Twitter on Thursday also took down two smaller state-backed operations originating from Russia and Turkey that were focused more on local audiences in those countries. The company deleted more than 1,000 accounts that posted material favorable to the ruling United Russia, as well as 7,340 accounts posting content promoting the Turkish President Recep Tayyip Erdogan’s conservative AK Parti.

Twitter is blocked in China, where the government operates one of the world’s strictest censorship regimes.

Last August, the company removed around 1,000 accounts that it deemed had ties to China and were “deliberately and specifically” attempting to influence narratives about Hong Kong, where ongoing anti-government, pro-democracy protests have posed a continual challenge to authorities.