The sex industry in Korea is employing new forms of prostitution such as a clandestine mobile sex trading system to avoid clampdowns, a recent police report showed, underscoring the need to devise more sophisticated ways of catching illegal sex traders.

Police found more than 6,600 cases of prostitution arranged on the new platforms, more than triple the number of cases they caught in 2010. The increase is about a 220 percent rise over the four-year period.

The latest methods of sex trade include the usage of online chat rooms, social networking sites and smartphone applications, the police said.

Online chat rooms often do not require users to disclose their names.

Online prostitution also allows buyers and sellers to constantly shift their transaction sites, from rented residences to local motels.