Twitter has suspended a large number of Chinese-language user accounts, including those belonging to critics of China’s government. It seems like a particularly ill-timed move, occurring just days before thirtieth anniversary of the Tiananmen Square massacre on June 4.

“A large number of Chinese @Twitter accounts are being suspended today,” wrote Yaxue Cao, founder and editor of the U.S.-based publication China Change. “They ‘happen’ to be accounts critical of China, both inside and outside China.”

Cao then went on to highlight a number of the suspended accounts in a Twitter thread.

The Chinese government reportedly began cracking down late last year on people who post criticism on Twitter. The author of that story, The New York Times’ Paul Mozur, has also been tweeting about the takedowns, noting that “suspensions seem not limited to accounts critical of China” and that it appears to be “an equal opportunity purge of Chinese language accounts.”

In response, Twitter’s Public Policy account said it suspended “a number of accounts this week” mostly for “engaging in mix of spamming, inauthentic behavior, & ban evasion.” It acknowledged, however, that some of the accounts “were involved in commentary about China.”

“These accounts were not mass reported by the Chinese authorities — this was a routine action on our part,” the company said. “Sometimes our routine actions catch false positives or we make errors. We apologize. We’re working today to ensure we overturn any errors but that we remain vigilant in enforcing our rules for those who violate them.”

By this point, the deletions had attracted broader political notice, with Florida Senator Marco Rubio declaring, “Twitter has become a Chinese govt censor.”

And while Cao acknowledged Twitter’s official explanation, as well as help she’s received from the company in the past, she said, “Per @Twitter’s explanation, it’s cleaning up CCP bots but accidentally suspended 1000s anti-CCP accts. That doesn’t make sense.”