Popular forum site Reddit has been added to Australia's world-first social media ban for children under 16 that starts next month.

Live-streaming platform Kick will also be included, bringing the number of sites targeted in the ban to nine. They include Facebook, X, Snapchat, TikTok, YouTube, Instagram and Threads.

From 10 December, tech companies can be fined up to A$50m ($32.5m; £25.7m) if they do not take "reasonable steps" to deactivate existing accounts for under-16s and prohibit new ones.

Each banned platform was chosen as their "sole or a significant purpose is to enable online social interaction," the government said, and more sites may be added given the "fast-changing" nature of technology.

"Delaying children's access to social media accounts gives them valuable time to learn and grow, free of the powerful, unseen forces of harmful and deceptive design features such as opaque algorithms and endless scroll," said Australia's eSafety Commissioner Julie Inman Grant.

Messaging services Discord and WhatsApp, and gaming platforms Lego Play and Roblox, will not be included, nor will Google Classroom and YouTube Kids.

Federal Communications Minister Anika Wells said the online platforms can target children with "chilling control" and the ban was about protecting children.

"We aren't chasing perfection, we are chasing a meaningful difference," she said.

It is unclear how companies will implement the ban, which is being closely watched by global leaders, but some of the potential methods include using official ID documents, parental approval and facial recognition technology.

Critics have raised concerns over data privacy and the accuracy of age verification software, with a recent report showing that the proposed methods all have risks or shortcomings.

Most Australian adults support the ban, according to polls, but some mental health advocates say it may cut kids off from connection, and others say it could push youngsters to even less regulated corners of the internet.

Instead, they say, the government should focus on better policing of harmful content on social media platforms and prepare children for the reality of life on the web.

An Australian influencer family who have millions of YouTube followers recently announced their decision to move to the UK to avoid the upcoming ban, namely so their 14-year-old daughter can continue to create online content.

YouTube was initially exempt from the ban, but in July, the government reversed its decision, saying the video-sharing site was "the most frequently cited platform" where children aged 10 to 15 years saw "harmful content".

Teens under 16 will still be able to view YouTube videos, but will not be permitted to have an account, which is required for uploading content or interacting on the platform.