Users of Kik messaging system, including children, report they are receiving sexually-explicit automated messages. (kik.com)

Police say they've received a number of complaints about sexually-explicit text messages on chat service largely used by young people.

Staff Sgt. John Guigon, of Alberta`s Internet Child Exploitation unit says some people using the Kik chat service are being targeted by an automated system.

“Basically you get an unsolicited text message either saying hi or maybe a little smiley face. Then if you choose to respond to it, that's where the rest of the stuff comes in. That's where the clever bot goes to work and tries to — ultimately they're trying to market something to you.”

Guigon says once a person responds, they get a nude photo and sexually-explicit messaging that directs them to an adult website.

Police believe it's an automated program coming from somewhere in the U.S.

Guigon says the operators of the Ontario-based company are aware of the problem and are trying to find a way to stop it.

The app does have an option to ignore new people, according to its website