Police have opened a preliminary investigation into alleged sex-for-favors cases involving a number of high-ranking officials and public figures.

Officials at the National Police Agency said they obtained intelligence that a local contractor bought sexual services for social elites in return for business favors. The list of influential figures involved in the case reportedly includes an official who serves in a vice ministerial post and the head of a large hospital.

The 51-year-old contractor, identified only with his surname Yoon, is accused of filming them having sex with women he hired for the purpose. Sources say that he might have used the footage to blackmail the officials for business favors.

“We have just launched a preliminary investigation to secure substantial evidence. We first need to contact the women allegedly involved in the case to get their testimonies,” a police official was quoted as saying by Yonhap News Agency. The official added that the police hadn’t recovered the videos yet. The police will consider imposing a travel ban on Yoon as soon as they secure circumstantial evidence of him arranging the secretive meetings.

Local reports claimed that Yoon hired about 10 women, including a housewife, a businesswoman and a musician, to perform sexual services for officials. They were allegedly often invited to Yoon’s luxurious country house in Wonju, Gangwon Province or karaoke sessions between 2008 and 2011. Actresses and models were also invited to parties at the house, reports quoting neighbors said.

The case came to the attention of police after a woman filed a complaint against Yoon and his colleague for rape and extortion late last year. The woman surnamed Kwon told police that she found a number of CD-ROMS in a car she had lent Yoon that showed big name officials and women having sex. The police asked Kwon to submit evidence to back up her claims but she said she had destroyed the discs. The prosecution dropped all charges against Yoon last month aside from one relating to an unregistered air gun.

Kwon claimed that she had lent Yoon 1.5 billion won ($1.34 million) in cash and that he had threatened to release another video of Yoon raping her while drugged after she asked to be paid back.

Some reports suggested that the police had already known that Yoon purchased sexual services for high-ranking officials but might have ignored the case in consideration of its impact on the new government.

The main opposition Democratic United Party called for a full, transparent investigation into the allegations.

“The police have probed the case for a while (but) seem to have no intention of uncovering the truth as they feel the pressure of investigating the case that (allegedly) involves high-ranking officials under the new government,” DUP spokesman Park Yong-jin said.

“Cheong Wa Dae and the leading members of the police need to make efforts to reveal the truth.”

By Cho Chung-un (christory@heraldcorp.com)