An Australian cyber regulator on Thursday said it has demanded Twitter explain its handling of online hate as the microblog has become the country's most complained-about platform since new owner Elon Musk lifted bans on a reported 62,000 accounts.

The demand builds on a campaign by the eSafety Commissioner to make the website more accountable after Musk, one of the world's richest people, bought it for $44 billion in October with a promise to restore its commitment to free speech.

The regulator has already called on Twitter to detail its handling of online child abuse material which it said has picked up on the website since Musk's takeover and subsequent job losses, including content moderation roles.

Commissioner Julie Inman Grant said she has sent a legal notice to Twitter demanding an explanation after one-third of all complaints she received about online hate concerned Twitter, even though the platform has far fewer users than TikTok or Meta's Facebook and Instagram.

"Twitter appears to have dropped the ball on tackling hate," Inman Grant said in a statement, which noted that the platform had reportedly reinstated 62,000 banned accounts since Musk's takeover, including high-profile accounts of individuals who espouse Nazi rhetoric.

"We need accountability from these platforms and action to protect their users, and you cannot have accountability without transparency and that's what legal notices like this one are designed to achieve," she said.

Twitter must respond to the eSafety Commissioner within 28 days or face a fine of nearly A$700,000 ($473,480) per day. It declined to comment when contacted by Reuters.

The demand comes as Australia approaches a referendum this year on whether to recognize Indigenous people in the constitution, prompting an increasingly intense debate about race.

Prominent indigenous television host Stan Grant had cited targeted abuse on Twitter when he announced a break from the media last month, the commissioner noted.

Specialist broadcaster National Indigenous Television also said it was taking a break from Twitter due to "the racism and hate that we experience every day on this platform," it said in a tweet last month.

Inman Grant said her letter called for Twitter to explain its impact assessments when reinstating banned accounts, how it engaged with communities who were subject to online hate, and how it was enforcing its own policies which ban hateful conduct.