Australia’s cyber watchdog has called on Twitter, which is owned by multi-billionaire Elon Musk, to explain its handling of online hate.
The country’s online safety commissioner says Twitter has become the most complained about platform.
Twitter has been 28 days to respond to the regulator or face potential fines of hundreds of thousands of dollars.
Mr Musk bought the firm last year for $44bn (A$64bn; £34.5bn) and promised to protect free speech on the platform.
A legal notice was sent to Twitter demanding an explanation after one-third of all complaints received about online hate concerned the platform, Julie Inman Grant said.
That is even though Twitter has far fewer users than TikTok, Facebook and Instagram.
The company has been told to respond to the watchdog within 28 days or face penalties of up to A$700,000 (£371,570; $475,300) a day for continuing breaches.