Telegram founder Pavel Durov has suggested that the Chinese government may have been behind a recent DDoS attack on the encrypted messaging service. Writing on Twitter, the founder called it a “state actor-sized DDoS” which came mainly from IP addresses located in China. Durov noted that the attack coincided with the ongoing protests in Hong Kong, where people are using encrypted messaging apps like Telegram to avoid detection while coordinating their protests.

The attack raises questions about whether the Chinese government is attempting to disrupt the encrypted messaging service and limit its effectiveness as an organizing tool for the hundreds of thousands of demonstrators taking part in the protests. Bloomberg reports that encrypted messaging apps like Telegram and FireChat are currently trending in Apple’s Hong Kong App Store, as demonstrators attempt to conceal their identities from Hong Kong’s Beijing-backed government.

IP addresses coming mostly from China. Historically, all state actor-sized DDoS (200-400 Gb/s of junk) we experienced coincided in time with protests in Hong Kong (coordinated on @telegram). This case was not an exception. — Pavel Durov (@durov) June 12, 2019

As well as using encrypted messaging apps, Bloomberg notes that protesters in Hong Kong are also covering their faces to avoid facial recognition systems. They’re also avoiding the use of public transit cards that can link location to identities.

Telegram’s Twitter account said that the service had been hit with “gadzillions of garbage requests,” mostly from IP addresses originating in China, as part of the DDoS attack which had stopped the service from being able to process legitimate requests from users. It said that these garbage requests tend to be generated by botnets, networks of computers infected with malware. “This case was not an exception,” Durov tweeted without elaborating.

Hong Kong’s protests are in response to a proposed law that would allow the city’s Beijing-backed government to extradite its citizens to China. Critics fear the law could be used to cement Beijing’s authority over the semi-autonomous city-state, where citizens tend to have a higher level of civil liberties than in mainland China.

As of 8PM Hong Kong local time on Wednesday, Telegram noted that the DDoS attack appeared to have stabilized, and assured users that their data is safe.