Crown Prince Nayef, the long-serving interior minister who led Saudi Arabia's crackdown against al-Qaeda's branch in the country and then rose to become next in line to the throne, has died. He was in his late 70s.
Prince Nayef bin Abdulaziz Al Saud, who became heir to the throne last year at the age of 78, was head of the country's interior ministry since 1975.
Nayef had traveled abroad for medical treatment and had "died outside the kingdom", Al-Ekhbariyah Television said, quoting a statement from the royal court.
He was shown on television greeting supporters in Geneva, Switzerland, three days ago.
Saturday's statement from King Abdullah said the prince would be buried after sunset prayers on Sunday in the Muslim holy city of Mecca.
The nature of his illness has not been made public.
Less than two weeks ago, his brother Prince Ahmed bin Abdulaziz was quoted as saying in a Saudi daily that the crown prince was in "good health" and that he would "soon" return to the kingdom.
Nayef was appointed crown prince after the death of his elder brother and predecessor in the role, Crown Prince Sultan.
Nayef's death unexpectedly reopens the question of succession in this crucial US ally and oil powerhouse for the second time in less than a year.
The 88-year-old Abdullah has now outlived two designated successors, despite ailments of his own. Now, a new crown prince must be chosen from among his brothers and half-brothers, all the sons of Saudi Arabia's founder, Abdul-Aziz.
The figure believed most likely to be tapped as the new heir is Prince Salman, the current defense minister who previously served for decades in the powerful post of governor of Riyadh, the capital.
The crown prince will be chosen by the Allegiance Council, an assembly of Abdul-Aziz's sons and some of his grandchildren.
Khaled al-Maeena, editor in chief of the Saudi Gazette told Al Jazeera that there was no cause for alarm.
"The secession in the Saudi household has always been very orderly, very organised", he said, adding that an announcement was expected after the first three days of mourning.
Salman, 76, seen as likely to continue Abdullah's cautious reforms, has long been viewed as the next most senior prince in the kingdom's succession.
Nayef, Abdullah and Salman are among the nearly 40 sons of Saudi Arabia's founder, Abdulaziz ibn Saud, who established the kingdom in 1935.
Salman was made defence minister in November and had served as Riyadh governor for five decades.
Source: Al Jazeera and agencies