A 12-year-old boy was arrested for allegedly raping an eight-year-old boy in Zola, Soweto police said on Friday.

"The two boys were alone in the house when the incident happened," said Inspector Kay Makhubela.

The mother of the eight-year-old saw there was something wrong with her child.

"She took him to a doctor who confirmed that the boy had been raped."

The 12-year-old was arrested and would face a charge of rape in the Protea Magistrate's Court on Friday.