ST. CLOUD, Minn. (AP) _ Authorities say there's an alarming amount of sex trafficking at illicit massage businesses in central Minnesota.

An investigation found that a Waite Park business police raided this month is one of a half-dozen in the area regularly advertising on websites known for selling sex. Riverwood Massage and Body Works owner Yanhang Lin has been charged with sex trafficking and promoting prostitution. Jail records don't list an attorney for her.

Officials say Minnesota doesn't regulate massage therapy at a statewide level. Local governments are responsible for regulation, which can create loopholes for traffickers.

The Central Minnesota Human Trafficking Task Force formed in March to address sex trafficking. The partnership involves organizations from Stearns County, St. Cloud, Waite Park and the Central Minnesota Sexual Assault Center.

A Minnesota Office of Justice Programs grant helped fund the task force.