The Korean Baseball Organization said it would be investigating pitchers Kim Kwang-hyun, Lee Yong-chan and Jeong Cheol-won.

It followed a media report accusing the trio of drinking alcohol during the preliminary round of the tournament in Tokyo.

All three denied the report's claims that they had been drinking on the evenings before South Korean defeats, however.

The team lost 8-7 to Australia on March 9 before a 13-4 defeat to Japan a day later.

South Korea won their other two games against Czech Republic and China but the damage had been done and they exited the tournament at the group stage for the third World Baseball Classic in a row.

Lee said he met a friend at a Korean restaurant on March 7 and Kim and Jeong said they had drinks after the Japan match on March 10.

The trio also denied reports that they had been accompanied by female waitresses but fans have been left angered by the revelations. 

Kim's club SSG Landers have removed the 34-year-old from their active roster and demoted him to the minor leagues as a result of the scandal.

"I'd like to apologise to all fans of baseball and my fellow players from the bottom of my heart for acting so foolishly during the national team tournament," Kim said, according to Yonhap. 

"I regret not exercising my self-control as a veteran of the team."

Lee and Jeong also said they regretted their actions.

Drinking alcohol is treated seriously in Korean sport.

In 2019, Olympic medallists Kim Tae-yun and Kim Cheol-min were among five speed skaters who were suspended by the Korea Skating Union for two months for drinking at their training centre in Seoul. 

Two South Korean baseball players were then removed from the country's Tokyo 2020 Olympic squad after breaking social distancing rules during the pandemic.

Second baseman Park Min-woo and pitcher Han Hyun-hee did not travel to Japan after meeting friends for drinks in Seoul.

South Korea won Olympic gold in baseball at Beijing 2008.