Signal could not be immediately reached for comment.

“What I can tell you is that as a principle, China’s internet is open, and the Chinese government manages internet-related affairs according to law and regulations,” Zhao said.

Zhao Lijian, a spokesperson for China’s ministry of foreign affairs, said at a daily news briefing on Tuesday that he was “not aware of the situation” around Signal being banned in China. In February, the popular social-audio platform Clubhouse was also shut down, shortly after Chinese users on the app started taking part in real-time audio discussions deemed sensitive by authorities, such as China’s mass detentions of Uighurs in Xinjiang. In China, services like Facebook, Google and Twitter have been blocked for years. Messages failed to send and calls did not go through. Users in China said Tuesday that they could not get the app to connect without a VPN service. The move to silence Signal, one of the few remaining messaging apps in China that allowed users to engage in encrypted messaging, comes as the country expands controls to shape public opinion and at times limit private discourse.

Signal messaging app