Cryptocurrency project Worldcoin has been ordered to cease operations in Hong Kong after breaching privacy rules through its iris scans and collection of face images, authorities said on Wednesday.

The Office of the Privacy Commissioner launched a probe into Worldcoin after raiding six of its premises around Hong Kong in January.

The project, founded by OpenAI CEO Sam Altman, provides a digital passport with free Worldcoin cryptocurrency tokens, but participants first have to have their faces and eyeballs scanned to verify they are human and unique.

More than 8,300 people in Hong Kong signed up, but many didn't know what they were agreeing to and the data taken from them was unnecessary and excessive, said Privacy Commissioner for Personal Data (PCPD) Ada Chung.

Worldcoin was found to have breached several parts of the Personal Data (Privacy) Ordinance, including by failing to explain to participants the risks regarding disclosure of their biometric data and by planning to keep personal information for up to 10 years in order to use it to train artificial intelligence models.

The privacy commissioner said another breach was that Worldcoin did not provide information to participants in Chinese.

"The PCPD was of the view that participants using Chinese as native language would not be able to clearly understand the relevant policies and practices, terms and conditions of the Worldcoin project, and hence there was a lack of transparency."

The privacy watchdog said members of the public should contact it immediately if they find that Worldcoin is continuing to carry out iris-scanning in the territory.