The woman was resting in her bedroom on Monday when she was raped by an 18-year-old neighbour, Lieutenant Joey Jeevan said.

An 80-year-old woman has been raped in her Esigodini home in Pietermaritzburg, KwaZulu-Natal police said on Wednesday.

The woman was resting in her bedroom on Monday when she was raped by an 18-year-old neighbour, Lieutenant Joey Jeevan said.

He and the woman's grandson had been watching television, but he disappeared when the 15-year-old went to make tea.

"It is alleged that he then went into his grandmother's bedroom and found the neighbour raping his grandmother," Jeevan said. He called for help.

Neighbours assaulted the youth.

"During the assault, the suspect mentioned that he and the grandson previously raped the granny together," said Jeevan.

Both were arrested and would appear soon in the Pietermaritzburg Magistrate's Court.

The youth was in a serious, but stable condition at a local hospital.

The woman was receiving counselling.