Elon Musk lashed out at Australia's prime minister on Tuesday after a court ordered his social media company X take down footage of an alleged terrorist attack in Sydney, and said the ruling meant any country could control "the entire internet".

At a hearing overnight, Australia's Federal Court ordered X, formerly called Twitter, to temporarily hide posts showing video of the incident a week earlier, in which a teenager was charged with terrorism for knifing an Assyrian priest and others.

X said it had already blocked the posts from Australian users, but Australia's e-Safety Commissioner had said the content should be taken down since it showed explicit violence.

"Does the PM think he should have jurisdiction over all of Earth?" Musk wrote in a post, referring to Prime Minister Anthony Albanese.

The billionaire, who bought X in 2022 with a declared mission to save free speech, posted a meme on the platform that showed X stood for "free speech and truth" while other social media platforms represented "censorship and propaganda".

Musk also wrote that "if ANY country is allowed to censor content for ALL countries, which is what the Australian 'eSafety Commissar' is demanding, then what is to stop any country from controlling the entire Internet?"

The pushback by the world's third-richest person sets up a new front in the battle between the world's largest internet platforms and countries and nonprofits seeking more oversight of the content hosted on them.

Last month, a U.S. judge threw out a lawsuit by X against the hate speech watchdog, Center for Countering Digital Hate. In Australia, the e-Safety Commissioner fined X A$610,500 last year for failing to cooperate with a probe on anti-child abuse practices; X is fighting that penalty in court.

Albanese hit back at Musk, saying the country would "do what's necessary to take on this arrogant billionaire who thinks he's above the law, but also above common decency".

"The idea that someone would go to court for the right to put up violent content on a platform shows how out-of-touch Mr Musk is," Albanese told the Australian Broadcasting Corp.

A spokesperson for e-Safety Commissioner Julie Inman Grant said the takedown notice was for the attack footage only, and not for "commentary, public debate or other posts about this event, even those which may link to extreme violent content".

"While it may be difficult to eradicate damaging content from the internet entirely ... eSafety requires platforms to do everything practical and reasonable to minimise the harm it may cause to Australians and the Australian community," the spokesperson added, in a statement.

Although Musk wrote in another post that X had "blocked the content in question for Australian IP addresses", the video could be seen on the platform by a Reuters journalist in Australia. A far-right senator also reposted the video on his X account.

On Tuesday, Facebook and Instagram owner Meta said it had used "internal tools" to detect and block copies of videos of the church attack and an unrelated, deadly stabbing at a shopping mall in Sydney two days earlier.

Meta said it was removing posts containing "any glorification or praise" of the incidents.

Alice Dawkins, executive director of internet policy non-profit Reset.Tech Australia, said Musk's comments fit "the company's chaotic and negligent approach to the most basic user safety considerations that under previous leadership, the platform used to take seriously."