China has started regulating the popular short-video apps like Douyin (TikTok) and Kuaishou aiming to limiting the amount of time spent on the screens by children.

According to a note published on the website of the Cyberspace Administration of China, all such apps will have to install a “youth mode” feature for parents from June to keep a tab on what children watch and for how long.

Short video apps are immensely popular in China, and according to reports about 650 million people watch them.

While the note did not specify any time limit that will be granted to children to be on the apps, both Douyin (globally known as TikTok) and Kuaishou said the screen time could be limited to merely 40 minutes a day, according to a report in China Daily.

The report said this regulation could hit advertising that had helped make Bytedance Ltd, the owner of TikTok, the world’s most valuable startup.

The regulator said the special youth mode would include cap on contacts and services that children would access. The children would not be able to access the app between 10 pm and 6 am, Douyin said in a WeChat post. Douyin will also switch on the youth mode automatically for a user.

No live-streaming to followers, depositing money on the platform, or tipping other users would be allowed either.

Kuaishou too posted a similar explanation on WeChat. It said the “youth mode’ would be switched on automatically as its system was designed to determine the age of a user.

In the US, TikTok will direct children under 13 to a similar “youth mode” restricting content and user interaction. In February, Bytedance was asked pay a whopping US$5.7 million fine to settle claims after TikTok illegally collected personal information from children.