Lethbridge Regional Police have charged a 14-year-old boy after an investigation into complaints about online harassment and threats.

Police officers responded to a complaint from two 13-year-old girls and a 14-year-old girl in February who reported receiving numerous harassing, sexually explicit and threatening messages via their social media accounts.

Police say the girls were told to provide sexually explicit photos of themselves and if they did not comply their social media accounts would be compromised and they would be physically harmed.

Through an investigation by School Resource Officers with help from the Internet Child Exploitation Unit, officers were able to identify the boy and seized various electronic devices for analysis.

He was arrested earlier this month but released with conditions.

The teenager is charged with three counts of extortion, child luring and one count of making sexually explicit images available to a child.