Authorities in Vietnam have expressed concern about the number of women being sent overseas as mail-order brides, after one was murdered by her South Korean husband eight days after she arrived in the country.
Following the murder, the 47-year-old husband turned himself in to police, saying he had heard a "ghost's voice" urging him to kill his 20-year-old wife. It later emerged he had been treated for schizophrenia more than 50 times in the past five years.
Last year it was reported that more than 40,000 Vietnamese women have married South Korean men and migrated there.
About 90 per cent of weddings between South Koreans and Vietnamese are arranged by illegal marriage brokers.
A foreign ministry spokesman said: "I think that it is not easy to identify which marriage is unlawfully brokered."