Chinese children and teens will be cut off from accessing the internet at night and have their smartphone use curbed under new rules unveiled on 2 August aimed at fighting internet addiction.

Under the restrictions, set to come into force on 2 September following a public consultation, anyone under the age of 18 will be cut off from accessing the internet with a mobile device between 10 pm and 6 am.

A tiered system for managing smartphone usage time will also be imposed, spanning a maximum of 40 minutes a day for those under the age of eight to two hours for 16- and 17-year-olds.

The new rules -- proposed by the Cyberspace Administration of China (CAC) -- are some of the most stringent in the world.

Parents will be able to bypass them if they wish, however.

The CAC said the rules would "improve the positive role of the internet, create a favourable network environment, prevent and intervene in minors' internet addiction problems, and guide minors to form good internet use habits".

The measures would build upon existing efforts to strengthen the online protection of minors, it added, including by "enriching age-appropriate content" and reducing "the influence of bad information".

Beijing authorities have pursued expansive regulation of the domestic tech sector in recent years, due in part to concerns over the risk posed to young people by digital technology.

In 2021, China capped the amount of gaming time for children with the stated aim of fighting addiction, and froze approvals of new games for nine months, hammering the bottom lines of many companies including sector titan Tencent.

And the latest decision suggests Beijing's regulatory clampdown on domestic tech giants continues.

Stocks of many leading Chinese internet firms fell following the CAC's announcement, with Tencent's Hong Kong-listed shares down 3%.

Meanwhile, web search, AI and online services giant Baidu saw its shares fall 3.75% during trading in Hong Kong.