A small group of mothers at Winfrey's Leadership Academy claim "the strict visitation rules are far from ideal and they want greater access to their children," according to The Hollywood Reporter.

The mothers say they are only allowed to see their daughters for two hours a month at the boarding school outside Johannesburg.

One mother, Angela Conradie, said her homesick daughter "phones me in tears sometimes, and then I don't know what to say to her".

But Winfrey has pressed on, opening a second school in South Africa. The Seven Fountains Primary School, funded by Oprah's Angel Network charity, cost $US1.6 million ($2 million) to create, according to a blog on The Hollywood Reporter's website.

The school is reportedly bigger than the first, with 25 classrooms, a computer centre and two sports fields.