The trio, aged 52 to 60, tried to lease a 500-ton cargo ship to smuggle all the illegal immigrants from Vietnam into Busan, the Korea Times quoted the municipal Police Agency as saying.
They had earlier colluded with a group of brokers in Vietnam in the plot, police said, adding that the Korean trio receives 8 million won (US$6,500) for every Vietnamese they could successfully bring over.
In total, the group of three could have made around US$490,000 if they had managed to smuggle all 100 Vietnamese into their country, after spending US$160,000 to hire the ship and crew.
The oldest member of the trio, identified only as S., was also wanted on charges of smuggling around 100 Chinese men into the country in an earlier case. Another also faces charges for bringing nine Koreans into Japan illegally in March, police said in a statement, adding that further investigations are ongoing.
Earlier this month, authorities in the resort island Jeju arrested 33 Vietnamese among 59 tourists who allegedly disappeared after arriving on a trip in January. Two brokers, both are Vietnamese, were also arrested for allegedly helping the fleeing tourists overstay and work illegally on the island.