A South Korean has been arrested for arranging sham marriages between homeless men and visa-seeking Vietnamese women, an immigration official said Friday. The 40-year-old man was held Wednesday by a special immigration investigation team for arranging the fake marriages, an official at Seoul's immigration office said. Three other alleged marriage brokers are being investigated by prosecutors. The brokers contacted homeless men at Seoul railway stations and promised them a free trip to Vietnam and up to three million won ($2,535) if they agreed to the fake marriages, the official told AFP on condition of anonymity. Vietnamese brides, who were seeking the right to live and work in South Korea, paid between $18,000-20,000. The homeless men were flown to Vietnam to marry, and the supposed couples then returned to South Korea for another wedding ceremony before the brides parted company with their spouses and disappeared. Investigators have booked 34 Korean men and 16 Vietnamese women for questioning, have deported 20 Vietnamese already, and are trying to trace another 120 people for suspected involvement in the scam, the official said. "Brokers in the past have used their acquaintances for sham marriages but paying homeless men is rare," another official told Yonhap agency. In late September, South Korea temporarily stopped accepting new migrant workers from Vietnam because about 2,000 Vietnamese had failed to leave after their work visas expired. The ministry estimated that about 160,000 foreigners of all nationalities were staying in South Korea illegally after their work or tourist visas expired.