Signal’s website was also inaccessible in the country.
Encrypted messaging app Signal appeared to no longer be working in China without the use of a virtual private network (VPN) on Tuesday morning, users in the country said.
China’s cyber authorities have become increasingly strict in recent years, widening the scope of apps, media outlets and social media sites banned in the country.
Signal’s press team did not immediately respond to a request for comment.
The Cyberspace Administration of China could not immediately be reached for comment.
On several occasions the app had previously stopped working in China without VPN with no reason given, only for usage to resume.
Signal saw a surge in downloads worldwide after January 6 when WhatsApp updated its privacy terms, reserving the right to share user data, including location and phone number, with its parent Facebook and units such as Instagram and Messenger.
Signal had been downloaded close to 510,000 times on iOS in China, and has been downloaded 100 million times worldwide on the App Store and Google Play combined, according to data company Sensor Tower.