Four advance scouts for Taiwan reportedly sneaked into one of South Korea's practice games by posing as umpire trainees, according to South Korean news agency Yonhap News.
South Korea's national team was playing a game in the city of Douliou against one of the country's pro teams, the NC Dinos, in preparation for the upcoming World Baseball Classic.
Taiwanese baseball's governing body apologized to Korean baseball officials by email on Tuesday, according to the report.
"We had our suspicions because there seemed to be too many people in the umpires' room," one Korean official was quoted as saying by Yonhap News. "They kept saying they were umpire trainees. But we later learned that they were really scouts and we ejected them from the stadium [in the fourth inning of the Dinos' 1-0 win]."
South Korean manager Ryu Joong-il said he was not bothered by the espionage, which had been attempted in the previous week as well, according to the report.
"In modern baseball, it's a battle of who gets the edge in collecting advance information, and there's nothing I can do about it," Joong-Il was quoted as saying. "I don't really care too much."
The 16-team World Baseball Classic is scheduled to run March 2-19, and Taiwan and South Korea are participants in the four-team, round-robin Pool B in the first round. The two teams are scheduled to meet on March 5 at Taichung Intercontinental Baseball Stadium in Taiwan.
The Netherlands and Australia are also part of the pool, which advances two teams into a modified double-elimination second round.
South Korea fell to Japan in the 2009 World Baseball Classic final, 5-3.