The Defense ministry Wednesday ordered a halt to the training of military reservists in an effort to curb influenza A (H1N1).
Drills will be suspended from Thursday to the end of this month to prevent the swine flu virus from spreading, the ministry said, adding that regular troops were also ordered to refrain from taking leave.
"The measure is aimed at minimizing the impact of the new flu" as the virus is highly contagious, according to AFP.
The decision came a day after South Korea raised its flu alert from "orange" to the highest "red" level, with 45 deaths attributed to the virus.
The government Tuesday announced it would also suspend a monthly defense drill for civilians.
South Korea retains three million reservists. Men must undergo part-time training annually for several years after completing a mandatory two years of military service.
South and North Korea have remained technically at war since their 1950-1953 conflict ended in a fragile armistice, not a peace treaty.