Saudi King Abdullah on Friday appointed one of his brothers, Moqren bin Abdul Aziz, as a deputy prime minister, making him second in line to the throne, the official SPA news agency said.
"Prince Moqren bin Abdul Aziz, adviser and special envoy of the king, has been named second vice president of the Council of Ministers," said the SPA report.
The king, 89, is the president of the Council, and Crown Prince Salman bin Abdul Aziz, 77, is the first vice president.
Like the crown prince, the 68-year-old Moqren is a son of Abdul Aziz bin Saud, who founded Saudi Arabia and died in 1953.
He has served as an adviser and special envoy of King Abdullah since July last year, previously serving as the head of Saudi intelligence.
The monarch's age and frequent hospitalisation have raised concerns about the future leadership of the ultra-conservative Gulf kingdom, a key player in the Middle East and major exporter of oil.