This is the second significant government change since the appointment of Prince Mohammed bin Salman, son of the king, as heir to the region's most powerful throne. Prince Mohammed serves as deputy prime minister under his father, King Salman.

State news agency SPA announced King Salman had replaced the country's labour, Islamic affairs and culture ministers.

The kingdom also announced it had set up a royal commission for the holy city of Mecca, which is expected to welcome millions of Muslim pilgrims for the annual hajj in August, to be chaired by Prince Mohammed.

The powerful Prince Mohammed has consolidated his grip on power since sidelining his cousin as crown prince last June. 

He has since spearheaded a string of policy changes in ultraconservative Saudi Arabia, including reinstating cinemas and allowing women to drive.