The 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, expanding the reach of banned apps, media, and social media sites in the country.
Signal’s website was also inaccessible in China on Tuesday morning.
The app was still available on Apple’s app store in China as of Tuesday morning, and the app and website appeared to be working normally in Hong Kong.
Signal’s press team did not immediately respond to a request for comment.
The China Cyberspace Administration could not immediately be reached for comment.
The app was no longer available in third-party Android stores in China, where Google services are heavily blocked.
On several occasions, the app had previously stopped working in China without a VPN for no reason, only to have use resumed.
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 Inc and units like Instagram and Messenger.
Signal had been downloaded about 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.
WeChat, Tencent’s all-in-one mobile application, is the dominant messaging application in China, with its payment functions and other services, it has more than one billion users worldwide.