Seoul, South Korea (CNN) South Korean authorities have vowed to "make an example" of 12 music students accused of conspiring to gain weight to avoid mandatory military service.

South Korea's Military Manpower Administration said the group had exchanged messages on KakaoTalk, a social messaging app similar to WhatsApp, about how to gain weight quickly.

Some of them reportedly consumed large amounts of protein powder, while others drank a thick aloe beverage on the day of their exam to appear heavier than they actually were.

"The Military Manpower Administration, via thorough investigation, will do our best to root out military service evasion crime and make an example of the violators so that a fair and just military service culture can take root," authorities said in a statement.

South Korea -- which is still technically at war with North Korea -- requires all men between the ages of 18 and 35 to perform at least 21 months of military service, though the country's Defense Ministry has pledged to reduce the term to 18 months by 2020.

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