The girls were 13 and 14 years old, Acting U.S. Attorney Laurie Magid said.
"The significance of this case is, we want people to fully understand that you cannot just go to another country and think you are out of the reach of law enforcement," Magid said.
"Andrew Mogilyansky believed if he were in another country, he could hand-pick orphans to first molest and then arrange for them to be child prostitutes in his child prostitution scheme," she said.
Mogilyansky was arrested Tuesday and was being held pending a detention hearing Friday. He is charged with traveling abroad to engage in illegal sexual activity and with committing sex crimes while overseas.
"We deny the allegations and we look forward to addressing them in court," said Mogilyansky's defense attorney, George H. Newman. He declined to comment further.
Four Russian men already have been convicted in that country in the case, authorities said.
Magid said she was unsure when Mogilyansky immigrated to the U.S., but she said he has been in the country "for quite some time." He has dual citizenship and authorities will argue that he is a flight risk and should be held until his trial, she said.
According to court documents, Mogilyansky ran several lucrative businesses including a company that distributes fire extinguishing equipment and a car export business. He valued his personal net worth in 2006 at $5.3 million, court papers stated.
He also is listed as chairman and founder on the Web site of the International Foundation for Terror Act Victims. The group's Web site asks for donations for children injured in the school attacks in Beslan, Russia, in which more than 330 people died after a nearly three-day hostage standoff in 2004.