Social media companies have collectively deactivated nearly five million accounts belonging to Australian teenagers just a month after a world-first ban on under‑16s took effect, the country's internet regulator said on Friday, a sign the measure has had a swift and sweeping impact.

The eSafety Commissioner said platforms had so far removed about 4.7 million accounts held by under-16s to comply with a law that went live on December 10.

"Today, we can announce that this is working," Prime Minister Anthony Albanese told a news conference.

"This is a source of Australian pride. This was world leading legislation, but it is now being followed up around the world."

The implementation of the ban is being closely watched by regulators worldwide. France, Malaysia and Indonesia have all said they will introduce similar laws, while some European nations and U.S. states are also discussing following Australia.

The figures represent the first government data on compliance and suggest platforms are taking significant steps to adhere to a law that could see them fined up to A$49.5 million ($33 million) for non-compliance, but does not hold children or their parents liable.

The tally is far higher than estimates circulated before the law and equates to more than two accounts for every Australian aged 10 to 16, based on population data. Meta previously said it took down some 550,000 underage accounts from its Instagram, Facebook and Threads.

The minimum age rule also applies to Google's YouTube, TikTok, Snapchat, and Elon Musk's X (formerly known as Twitter). Reddit has said it is complying but is suing the government seeking to overturn the ban. The government says it will defend itself.

Critics of the ban have said it will be difficult to enforce, and eSafety Commissioner Julie Inman Grant told the press conference some underage accounts remain active and it was too early to declare full compliance.

"We don't expect safety laws to eliminate every single breach. If we did, speed limits would have failed because people speed, drinking limits would have failed because, believe it or not, some kids do get access to alcohol," she said.

All companies that were initially covered by the ban said they would comply.

Some smaller social media applications reported a surge of downloads in Australia in the run-up to the December rollout, and eSafety said it would monitor what it called migration trends. But it said the initial download spikes had not translated into sustained usage.

A study with mental health experts will track the ban's long-term impact for several years.