A Calgary man pleaded guilty to luring three girls over the internet, less than two weeks after being acquitted of similar charges.

Matthew Allan Armstrong, 28, pleaded guilty on Friday to six charges including luring a person under the age of 16 for the purpose of facilitating sexual interference or sexual touching, and breach of bail conditions.

The incidents involved a 15-year-old girl, as well as an undercover police officer pretending to be a teenage girl.

Armstrong also admitted to trying to lure an adult woman, who was inspired by an American TV show called To Catch a Predator to pose as a teenage girl online, defence lawyer Balfour Der told a Calgary newspaper.

The incidents happened between May 19 and June 3, when Armstrong was free on bail in another case where he was charged with luring and sexually assaulting a 13-year-old girl.

In October, a judge found Armstrong not guilty in that case, because there was reasonable doubt the accused knew how young the girl was.

The judge also took into account Armstrong's disability, myotonic dystrophy, which causes muscle weakness and delayed behavioural development.

Armstrong will remain in custody until his sentencing on Dec. 19.