CALGARY - Lethbridge police say they're troubled by the discovery of a 13-year-old female prostitute whose presence has led to two arrests in the southern Alberta city.

Following an investigation lasting "a couple of weeks," Lethbridge Regional Police have charged two Lethbridge men in the case, one an alleged John for allegedly purchasing the girl's services, the other as her accused pimp.

The girl's age came as a shock to police, said Insp. Bill Kaye.

"It's a 13-year-old girl, it's very disturbing it's occurring in this city," said Kaye.

"It's the first time I'm aware of a girl this young working in our downtown ... it's very concerning."

No charges are being laid against the girl, who's in the care of provincial child welfare officials, he said.

Police allege the girl had engaged in an act of prostitution with a man in his 60s in downtown Lethbridge on Feb. 13.

Accused of being a John is Robert John Gerard, 61, who's charged with sexual assault, sexual interference, procuring a youth for sex and invitation to touching.

He's been released under the condition he stay away from anyone under the age of 16 unless accompanied by an adult and is due in court March 1.

Memphis Mathew Gros Ventre Boy, 32, is charged with procuring prostitution and invitation to sexual touching.

He's been released and ordered to stay away from the girl and from Lethbridge's downtown.

Police say Gros Ventre Boy, who's to appear in court Feb. 27, was known to them, though Gerard was not.