Afrikaans-language newspaper Beeld reported the children -- who were tortured with an electric cable and blowtorch -- never left the house and have never been to school.
The paper claimed he allegedly kept his wife as a sex slave.
Police confirmed they detained the 36-year-old on Friday for the suspected abuse of five children aged between two and 16 years.
"The charges against him are attempted murder and assault," police spokesman Lungelo Dlamini told AFP.
"He allegedly abused five of his kids."
Beeld quoted a neighbour as saying: "We didn't know the children existed. I didn't know that for years we've been living next to a monster.
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