Australia said on Wednesday it will add YouTube to sites covered by its world-first ban on social media for teenagers, reversing an earlier decision to exempt the Alphabet-owned video-sharing site and potentially setting up a legal challenge.

The decision came after the internet regulator urged the government last week to overturn the YouTube carve-out, citing a survey that found 37% of minors reported harmful content on the site. "Social media have a social responsibility and there is no doubt that Australian kids are being negatively impacted by online platforms, so I”m calling time on it," Prime Minister Anthony Albanese said in a statement.

"I want Australian parents to know that we have their backs."

The decision broadens the ban set to take effect in December. YouTube says it is used by nearly three-quarters of Australians aged 13 to 15, and should not be classified as social media because its main activity is hosting videos.

"Our position remains clear: YouTube is a video sharing platform with a library of free, high-quality content, increasingly viewed on TV screens. It”s not social media," a YouTube spokesperson said by email.

Since the government said last year it would exempt YouTube due to its popularity with teachers, platforms covered by the ban, such as Meta”s Facebook and Instagram, Snapchat and TikTok, have complained.

They say YouTube has key similarities to their products, including letting users interact and recommending content through an algorithm based on activity.

Artificial intelligence has supercharged the spread of misinformation on social media platforms such as YouTube, said Adam Marre, chief information security officer at cyber security firm Arctic Wolf.

"The Australian government”s move to regulate YouTube is an important step in pushing back against the unchecked power of big tech and protecting kids," he added in an email.

The reversal sets up a fresh dispute with Alphabet, which threatened to withdraw some Google services from Australia in 2021 to avoid a law forcing it to pay news outlets for content appearing in searches.

Last week, YouTube told Reuters it had urged the government "to uphold the integrity of the legislative process". Australian media said YouTube threatened a court challenge, but YouTube did not confirm that.

The law passed in November only requires "reasonable steps" by social media platforms to keep out Australians younger than 16, or face a fine of up to A$49.5 million.

The government, which is due to receive a report this month on tests of age-checking products, has said those results will influence enforcement of the ban.