A young Singapore couple has been charged with extortion in a scheme to develop relationships with men online and then blackmail them, officials say. Yap Siew Ting, 17, and Soh Zhi Ren Alexander, 21, allegedly tried to blackmail 22-year-old Ng Yong Cheng out of S$6,000 (about $4,800) by threatening to upload a nude video of him to the Internet on Jan. 8, 2012. Two other suspects were arrested in the case, but are yet to be charged. If the two are convicted, they could serve two to seven years in prison, as well as be sentenced to caning, Channel News Asia reported. Yap and Soh are suspected to be behind a group which blackmails men by persuading them to undress on camera, then using the photos and videos to extort money from them. Often, the contact took place on the popular Web site Alamak.com.