Daniel Stephen Johnson, 35, allegedly sexually assaulted three underage girls at Hope Transitions, the orphanage he ran in Cambodia, the Phnom Penh Post said Wednesday.
The alleged victims were between 13 and 15 years old.
He was arrested Monday in connection with the U.S. cases, but will not be extradited until he is tried in Cambodia, authorities said.
"He must face his charges, must be convicted by a Cambodian court and serve his sentences in Cambodia first ... before he is extradited to face his criminal cases in his own country," said Major General Pol Pithey, the chief of the Anti-Human Trafficking and Juvenile Protection Department of the Ministry of Interior.
A senior police official told the Post that Johnson is wanted in connection with five underage rape cases in the United States.