Metro Manila (CNN Philippines, October 1) — Nearly 100 women, mostly Chinese nationals, were rescued at an alleged prostitution den that is posing as a karaoke bar in Makati City on Tuesday.

Ninety-one Chinese women and four Filipino women were rescued after National Bureau of Investigation operatives raided the Skytop International Club along Yakal Street.

Four Chinese nationals and 4 Filipinos were arrested.

Atty. Romeo Astrero Jr. of NBI Anti-Fraud Division said the hidden prostitution den was brought to their attention when a Chinese national reported it to them. Their operatives conduct surveillance for a week before conducting the raid.

He said the KTV-slash-prostitution den is exclusively for Chinese nationals and other nationalities cannot enter without help from the Chinese. He said there has to be an advanced booking through an app, which has to be shown before entering the establishment.

"Kailangan mo i-book sa cellphone application. Titignan kung may booking ka at saka ka makakapasok. Bibigyan ka ng VIP room, mamimili ka ng babae — Chinese, may Pilipino rin, papipiliin ka," he said.

[Translation: You need to make a booking through a cellphone application. You can only go in if you have the online booking. You will be given a VIP room where you can pick Chinese or Filipino women.]

Astrero said they are convinced the KTV is a prostitution den. He said the customers would be transacting for an "entertainer" for around P15,000 fee. There is also an option to bring the women out, he added.

"Noong una dine-deny na may prostitution, pero nakita niyo naman may used condoms sa loob ng VIP room. May nangyayaring prostitution sa loob," he said.

[Translation: They were trying to deny there was prostitution, but as you can see, used condoms littered the VIP room. Prostitution is happening here.]

NBI said they are looking to file cases against the eight people arrested for violation of the Anti-Human Trafficking Law and Cybercrime Prevention Act for the use of a cellphone app to illegally book women.