South Korea says 10 former and current diplomats posted at its Shanghai consulate will be punished after an investigation found some diplomats had "inappropriate relationships" with a Chinese woman.
The Foreign Ministry said Friday it will quickly and sternly deal with those involved.
The investigation released by the prime minister's office says some of the diplomats issued visas to Chinese citizens without properly reviewing applications.
Documents with phone numbers for high-ranking South Korean officials also were leaked but are not considered state secrets.
South Korea started investigating two weeks ago after receiving a tip.