Four Chinese state-run news agency staff have been suspended for a typographical error suggesting President Xi Jinping had resigned.

Two reporters from the South Africa department and two editors at the China News Service were punished for an article written inaccurately on Xi's address to the China-Africa summit in Johannesburg.

The Chinese word for "speech" was replaced with "resignation", the Information Centre for Human Rights and Democracy said on Sunday.

Some 20 state-run media carried the report on Saturday until a correction appeared about one hour, 20 minutes later, the Hong Kong-based advocacy group said.

Although the characters are different, the word for "speech" in its mainland Chinese pinyin romanisation is "zhici" - whereas "resignation" is "cizhi".

The word processor converts pinyin to Chinese characters.