Saudi Arabia's King Abdullah left for a private visit to Morocco on Tuesday and appointed his younger brother, Crown Prince Salman, to run the affairs of the world's top oil exporter in his absence, the royal court said.
The movements and health of the elderly monarch and other senior royals in the US-allied, conservative Islamic kingdom are closely watched because of their immense executive power.
"Due to our intention to travel outside the kingdom today, Tuesday ..., we have appointed, by this order, his royal highness brother Salman bin Abdulaziz, the crown prince, to run the affairs of the state and look after the interests of the people during our absence from the kingdom," the royal court said in a statement carried by state news agency SPA.
The agency later said that King Abdullah had departed the Red Sea port city of Jeddah, where the monarch had been staying since last month as is customary in the summer, for Morocco.
King Abdullah last year also spent time in Morocco on a private holiday, before developments in the crisis in Syria's civil war forced him to cut his holiday short.
The monarch, who is thought to be 91, has been making fewer public appearances in recent months, leaving Crown Prince Salman to chair most of the weekly cabinet meetings.
The king had an operation in November 2012, one of several in recent years, which kept him in hospital for nearly a month.
King Abdullah in March appointed Prince Muqrin bin Abdulaziz, a former Saudi intelligence chief, as deputy crown prince, making him second-in-line for the throne.