South African police have arrested a former staff member of Oprah Winfrey's school for disadvantaged girls, charging her with abuse and sexual assault.

The 27-year-old woman had worked as a dormitory matron at the Oprah Winfrey Leadership Academy for Girls, police Supt. Lungelo Dlamini said Friday.

The actual arrest occurred Thursday.

"Charges -- including alleged assault, indecent assault, criminal injury and soliciting underage girls to perform indecent acts -- are being investigated against her," Dlamini said.

At least seven alleged victims have submitted statements, he said.

The accused, who had been relieved of her duties earlier this week, is in police custody. She is expected to appear Monday in Sebokeng magistrate's court, located south of Johannesburg, Dlamini said.

Winfrey will not comment before a news conference scheduled for Monday, a South African-based spokeswoman said on her behalf.

The talk show superstar opened the academy in early January, an event attended by celebrities such as singer Tina Turner and film director Spike Lee. Even former South African president Nelson Mandela was there.

Winfrey had promised Mandela the school years ago. The institution is designed to give 152 girls, who have excellent grades but are from deprived backgrounds, a quality education. The school, located at Henley-on-Kipp, which is near Johannesburg, is free for the students.

Winfrey has been forthcoming about her own past as a victim of sexual abuse. She has also offered a reward for those who provide information to bring at-large child abusers to justice. Eight of 10 have been captured so far.

"Nothing is more serious or devastating to me than an allegation of misconduct by an adult against any girl at the academy," she said in a statement released Oct. 17.

Local media reported that Winfrey has already made a tearful apology to the students of the school and their parents during a recent meeting with them.

"I've disappointed you. I'm so sorry. I'm so sorry," she has been quoted as saying.

Winfrey told the meeting that she had given the alleged victims ways they could contact her at any time, including her personal email address and telephone number.

With files from The Associated Press