South Korea has ordered Facebook owner Meta Platforms to pay 21.62 billion won ($15.67 million) in fines after finding it had collected sensitive user data and given it to advertisers without a legal basis, Seoul's data protection agency said.

The U.S. tech giant obtained information from about 980,000 South Korean Facebook users on issues such as their religion, political views and sexuality while failing to seek agreement from users, the Personal Information Protection Commission said in a statement on Tuesday.

The information was then used by some 4,000 advertisers, the agency said.

A Meta Korea official declined to comment.

"Specifically, it has been found that (Meta) analysed user behaviour data such as pages they liked and advertisements they clicked on Facebook and created and managed advertising themes related to sensitive information," the commission said.

This included users being categorised for example as being North Korean defectors, following a certain religion, or identifying as a transgender or gay person, the agency said.

Meta had also unfairly declined a request by users to access personal information and failed to prevent data on about 10 South Koreans from being leaked by hackers, the agency said.