South Korea's telco watchdog has fined Facebook for intentionally rerouting network connections, causing an access slowdown for local users.
The US company was fined 396 million won, or $370,000, by the Korea Communications Commission (KCC) and ordered to correct its practice.
Facebook was in dispute with local internet service providers SK Broadband, LG Uplus, and SK Telecom over network fees from 2016 to 2017.
The firm originally used a cache server operated by KT, which SK and LG have been using, but a law change in 2016 brought in a measured rate system, which complicated the fee issue. Facebook now has to pay all three providers.
To circumvent the law, the company rerouted SK and LG's network to servers in Hong Kong without warning that it caused a slowdown of 2.4 to 4.5 times compared to local access, the KCC said.
Facebook said the decision was "unfortunate" but that it will work with local telcos to provide the best services for consumers.
Local telcos declined to comment.