Navi Pillay, the first non-white woman to serve as a high-court judge in South Africa, said Internet privacy is as important as any other category of human rights.
Pillay said she will prepare a U.N. report on protection of the right to privacy, following the leak of classified documents by former National Security Agency analyst Edward Snowden exposing U.S. and British spying and the gathering of personal data.
The former international criminal court judge said her previous encounters with serious human rights abuses did not make her take online privacy less seriously.
"I don't grade human rights," she said in a BBC radio interview. "I feel I have to look after and promote the rights of all persons. I'm not put off by the lifetime experience of violations I have seen.
"Combined and collective action by everybody can end serious violations of human rights," she said, citing the international uproar to that led to the end of South Africa's apartheid policy.
"That experience inspires me to go on and address the issue of Internet [privacy], which right now is extremely troubling because the revelations of surveillance have implications for human rights."
Working under a resolution passed by the United Nations, Pillay will prepare and publish a report on the protection and promotion of privacy "in the context of domestic and extraterritorial surveillance ... including on a mass scale."
"People are really afraid that all their personal details are being used in violation of traditional national protections," she said.