The US chat show host - who opened the Leadership Academy for Girls, a boarding school for the gifted near Johannesburg, in January - broke down in tears as she begged for forgiveness from parents over the claims.

Oprah said at an emergency meeting at the school: "I've disappointed you. I'm so sorry. I'm so sorry."

The 53-year-old TV star canceled appointments to fly to South Africa for the second time in two weeks after allegations emerged that one of the matrons fondled a girl and that other pupils had been physically abused.

One student claimed a matron grabbed her by the throat and threw her against a wall, while other girls have said the "dorm parent" swore and screamed at them, assaulted them and sexually fondled at least one girl.

The alleged incidents came to light when one of the pupils ran away from the $46 million school, which Oprah opened to provide quality education to underprivileged girls.

Oprah - who has spoken openly about being abused as a child - has since given the girls her personal telephone number, her email address and her postal address so they can contact her at any time.

South African police and the Family Violence, Child Protection and Sexual Offenses Unit are now investigating the matter.

Two weeks ago, Oprah placed the matron suspected of being at the center of the allegations on leave, along with at least one other matron and the principal.