Saudi Arabia's King Abdullah has appointed his son Prince Turki bin Abdullah as the governor of Riyadh Province.

Prince Turki's elevation to one of the most important positions in the kingdom comes months after another son of the king, Prince Mishaal bin Abdullah, was made governor of Makkah Province.

The Saudi line of succession does not pass directly from father to son, as in European monarchies, but has moved along a line of brothers born to the country's founder King Abdulaziz who died in 1954.

King Abdullah, who is over 90, has made a series of changes and appointments over the past two years. The most recent was the appointment of Prince Muqrin, the youngest of King Abdulaziz's sons, as deputy crown prince, a newly created position that makes him next in line to rule after King Abdullah and Crown Prince Salman.

NEW DEPUTY DEFENCE MINISTER

Prince Turki's promotion from his previous job as deputy governor was made in a series of royal decrees carried on state media, which also removed the deputy defence minister, Prince Salman bin Sultan, from his post.

Prince Salman, a younger brother of former intelligence chief Prince Bandar bin Sultan, and a key figure in organising Saudi Arabia's support for Syrian rebels, had met visiting US Defense Secretary Chuck Hagel on Tuesday evening.

The decrees said Prince Salman had left the defence ministry position at his own request. He was replaced by the outgoing Riyadh governor Prince Khaled bin Bandar.

Until 2011, the position of Riyadh governor had been held for five decades by Prince Salman bin Abdulaziz, who was made crown prince in 2012.

The province is home to the country's capital. Prince Turki bin Abdullah was born in 1970. - Reuters