Police in Medicine Hat are advising Albertans against trying to bait men looking for sex online by posing as underage girls and then filming their encounters and posting the videos online as a form of social-media shaming.

The practice has become increasingly common in recent months, led in particular by a Calgary man who has posted dozens of videos since November of him confronting "creeps" who agreed to meet up with him after he pretended to be a young girl via online messages.

Staff Sgt. Cory Both with the Medicine Hat Police Service said an officer on a routine patrol Wednesday night encountered two men who had just finished confronting a target of their own and claimed to have been "mentored and trained" by the Calgary creep-catcher leader.

One of the men even claimed to be the president of a Medicine Hat chapter devoted to the activity.

Police took the pair in for further questioning and they were quite open about their activities, Both said, even admitting that they had two more meetings lined up for later on.

Screenshots of conversations with a target posted online by a Calgary-based "creep catcher" who has also uploaded dozens of videos of confrontations he has filmed with men after arranging meetings by posing as an underage girl online. (Screenshots)

Officers tried to discourage the Medicine Hat men from continuing to act as vigilantes but the message didn't appear to get through.

"They weren't dissuaded, that's for sure," Both said.

"They were committed to the cause and they left here with a warning that, if they continue, there could be all kinds of consequences for them."

Police issue public plea

The situation prompted police to issue a public statement Thursday, warning Albertans that this type of "vigilante activity" is mostly legal but some of it treads "precariously close" to criminal activity.

"Creating fictional online profiles using stock photos or pilfered images from another person's social media accounts could create grounds for an identity theft or identity fraud complaints and/or arrest," the release states.

"Individuals acting on their own may also create a criminal harassment, public mischief or obstruction offence, if they are overly zealous in their efforts."

'Growing concern'

The trend is "a growing concern throughout Canada and the United States," police added, noting it could also lead to civil defamation lawsuits if allegations are presented online without clear evidence.

"Anytime a member of the public has information on a potential online crime, they are encouraged to report their concerns to police immediately," police said.

"Independent vigilante investigations create complications for the courts and ultimately subvert true justice."