China's most popular messaging app has been blocked in Russia.

Moscow's communications regulator has added WeChat to its list of prohibited websites, according to Russian state news agency TASS.

The messaging app ran afoul of laws requiring companies that distribute information online to register with government authorities in Russia.

Operated by tech giant Tencent (TCEHY), WeChat has about 900 million monthly active users, the vast majority of whom are in China.

Tencent said in a statement Monday that it's "in discussions with relevant authorities regarding the situation" in Russia. WeChat has been blacklisted since at least Friday, according to the TASS report.

Related: China's WeChat is censoring group chats without users' knowledge

Russian authorities are increasingly viewing the internet as a serious political threat and are trying to copy China's model of internet control, according to recent analysis from New America, a Washington-based think tank.

Last year, the architect of China's vast online censorship apparatus, known as the Great Firewall, was invited to speak at a forum on internet safety in Moscow. In 2015, Russia passed a law requiring companies to store data about Russian citizens in the country. That law appears similar to Chinese regulations preventing data collected in China from leaving the country.

As for WeChat, the messaging platform is no stranger to censorship, though it's usually on the other side of the restrictions.

Related: China's cybersecurity law slammed by rights groups and businesses

In China, WeChat messages containing keywords mentioning sensitive topics like the Tiananmen Square massacre of 1989 or Tibet are blocked and censored.

In Russia, WeChat is just the latest casualty in Moscow's clampdown on international social media platforms. Last week, the communications regulator blocked Line (LN), Blackberry (BBRY) and Imo messengers, according to Russian news outlet RT. In November, it banned LinkedIn, the social network for professionals that's owned by Microsoft (MSFT).

Line, one of Japan's biggest messaging apps, said in a statement that it's investigating the situation. The company also appeared to take a veiled swipe at Russia's law on data collection.

"Line is committed to protecting user privacy, according to Japanese law," it said.