A South African court on Monday found a former employee of a school founded by U.S. talk show host Oprah Winfrey not guilty of sexually assaulting students, a prosecutor's office spokesman said.

"She was found not guilty," Mthunzi Mhaga, a spokesman for the National Prosecuting Authority, told Reuters.

Tiny Virginia Makopo faced 14 charges of assault, including the sexual assault of students, the SAPA news agency said.

Much of the testimony was held behind closed doors at the Magistrates Court in Sebokeng to protect the students who are minors, it said.

Winfrey spent millions of dollars to open The Oprah Winfrey Leadership Academy for Girls in a town south of Johannesburg in early 2007 to provide a high-quality education for impoverished girls.