A member of the vigilante group Creep Catchers is facing charges of harassment and mischief after he accosted a Lacombe man, police say.

Lacombe police charged a 37-year-old Red Deer man Sunday after investigating a series of conversations between the suspect and a man in his 20s on social media.

Acting Police Chief Lorne Blumhagen said the suspect used false pretences to convince the complainant to meet in person in Lacombe, about 125 kilometres south of Edmonton.

The suspect accused the man of trying to communicate with someone online for sexual purposes.

Blumhagen said the man was trying to walk away, but was impeded by the suspect who made comments of a "threatening nature."

The suspect then posted a Facebook video of himself accosting the man.

Creep Catchers is a vigilante group that aims to expose people it believes are targeting children for sexual activity.

Blumhagen said vigilante-type tactics are not only dangerous but "irresponsible because they're making assumptions based on very little information.

"They suspect somebody might be committing an illegal act," he said. "However, they aren't advising police or giving police the opportunity to investigate what claims they may have."

The accused is due in provincial court in Red Deer on Friday.