President Yoon Suk-yeol speaks to reporters as he arrives at the presidential office in Seoul, Oct. 17. Yonhap

President Yoon Suk-yeol said Monday the antitrust watchdog is looking into the issue of top mobile messenger KakaoTalk dominating Korea's mobile messenger market, after the service ground to a halt due to a server outage over the weekend.

A fire started the outage at a data center used by Kaka, the messenger app's operator, on Saturday afternoon, causing major disruptions to everything from everyday communication to ride-hailing and public services tied to the app.

The weekend standstill exposed a major vulnerability in one of the world's most wired nations, leading to questions about Kakao's dominance in the communication market and the need for government intervention to address structural flaws.

"I'm a believer in a free market economy that respects the freedom and creativity of businesses, but that is premised on the market rationally distributing resources and income according to a fair and competitive system," Yoon told reporters as he arrived for work.