According to AFP, Saudi Arabia's 90-year-old King Abdullah on Thursday (March 27) appointed his half-brother Moqren, 69, as the next heir to the throne of the world's largest exporter of crude oil.
The decision, announced in a royal decree, comes as a source close to the circle of power told AFP that current Crown Prince Salman, 79, was sick and "may decide not to claim the throne" because of his ill health.
Under the rules of succession in Saudi Arabia, power passes from brother to brother under the right of primogeniture among the sons of Abdul Aziz bin Saud, the kingdom's founder.
The King made public his decision on the eve of a visit by US President Barack Obama, who is expected in Riyadh late on Friday afternoon (March 28).
Under Thursday's decree, Prince Moqren, currently second deputy prime minister, is named as the next crown prince.
COMMENT: The act is irrevocable, the decree said, stipulating that "nobody can change this decision," which takes effect from Thursday.
"King Abdullah wants to assure a smooth succession by this internal reorganization of power" within the family, adding that the decision had been "taken in agreement with Crown Prince Salman."
"It was passed by 27 of the 34 members. Others had reservations or abstained in the vote."
The son of a Yemeni mother, and the father of thirteen children including six sons, Prince Moqren is the youngest of the 35 sons of the country's founder.
Prince Moqren joined the air force in 1968 before becoming governor of Hael in the north and later the holy city of Medina in the west.
From 2006 until July 2012 he headed the intelligence services before being named counsellor to and special envoy to King Abdullah.
The source said the King also informed the board of his intention to appoint his son Mitab as second deputy premier.
He added that Prince Salman asked that support be given to his son, Prince Mohammed, to be appointed to the defense portfolio.