Koreans rank among the top clients of prostitutes in Southeast Asia, ahead even of Japanese and Chinese travelers, extensive research suggests.

The conclusion comes from research by the Korean Institute of Criminology that included field surveys in Vietnam, Thailand, Cambodia and the Philippines, study of UN reports and other relevant documents, interviews with local social workers and neighbors, and arrest records at local police stations.

According to the KIC, social workers in those countries claim that Korean tourists outnumber all other nationalities in terms of the frequency of their visits to prostitutes. There are no hard data to support those claims, but a tally of tourists who frequent bars linked to prostitution and accounts of sex workers appear to confirm them.

In the Philippines, for example, a total of 920,000 Koreans visited in 2011, making them the biggest group of foreign visitors. Cambodia saw 340,000 Korean visitors over the same period, also the biggest group except visitors from neighboring Vietnam. In Vietnam, Korean tourists make up the second largest group after Chinese.

In its 2010 report, the UN Office on Drugs and Crime said Korean men were the prime clients of child prostitutes in Cambodia, Thailand and Vietnam.

The U.S. State Department's annual report on human trafficking also points to Korean men as being the main clients of child prostitutes in Southeast Asia and Pacific islands, and added that the Korean government has yet to crack down on offenders or attempted to curb the trend.

The KIC report speculates that the main cause of the situation is a lack of guilt among Korean tourists about paying for sex. A survey on 900 people by the institute in October last year found that 77.7 percent were not aware that paying for sex overseas is an offence under Korean law, and 78.5 percent thought their chances of getting punished were low.

Another cause of the problem, according to the report, is that tourists are frequently solicited to pay for sex. Korean tourists in their 20s and 30s are lured into purchasing tour packages involving prostitution on the Internet, while those in their 40s and 50s are approached by travel agents. Neither practice met with much restraint.

The KIC said many tourists do not go on trips aiming to pay for sex, but local tour guides take them to insalubrious establishments as part of the package.