South Korea has fined Facebook-parent Meta more than US$15 million for illegally collecting sensitive user information from nearly a million people without consent and sharing it with advertisers, the country's data watchdog said on Tuesday.

The firm, which also owns Instagram, ran afoul of laws prohibiting the use of information on political opinions, religious beliefs and people's sex life unless the individual provides explicit consent, Seoul's Personal Information Protection Commission added.

It said that the tech giant collected sensitive information from around 980,000 domestic users in South Korea through their Facebook profiles.

This included details about their religious beliefs and whether they are in a same-sex relationship.

The watchdog said it had confirmed that such information was provided to advertisers by Meta, with around 4,000 advertisers using it.

Meta "analysed user behaviour data, including pages liked and ads clicked on Facebook", to create and implement targeted advertising related to "sensitive themes" such as transgender issues, homosexuality and North Korean defectors, officials said.

The commission said on Tuesday it had decided to fine Meta 21.6 billion won or US$15.6 million.

It added that it "also ordered the company to establish legal grounds for processing sensitive information, implement safety measures, and respond diligently to users' requests for access to their personal data". (AFP)