RIYADH: Saudi Crown Prince Nayef bin Abdul Aziz, a half brother of King Abdullah and the kingdom's long-serving interior minister, died on Saturday, state television announced.

The 79-year-old Prince Nayef, who recently left Saudi Arabia for medical treatment, had “died outside the kingdom,” said Al-Ekhbariyah Television, quoting a statement from the royal court.

His funeral would be held on Sunday after sunset prayers in the Muslim holy city of Mecca, after his body is repatriated.

Powerful Nayef, who led an iron-fisted crackdown on al Qaeda following a wave of attacks in Saudi Arabia between 2003 and 2006, became heir to the throne in October last year following the death of crown prince Sultan, his full brother.

Nayef was the middle prince of the Sudairi Seven, the formidable bloc of sons of King Abdul Aziz by a favorite wife, Princess Hassa al Sudairi.

No one is officially in line to replace Nayef, but his brother Prince Salman, who took over the porfolio of defence minister after Sultan's death, appears a strong candidate.

Prince Nayef had been abroad on several occasions this year for medical reasons, including to Algeria, the United States, and Switzerland, where he was seen a few days ago.

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.

On May 26, state news agency SPA said Prince Nayef had left the country for medical tests abroad for the second time in less than three months, without naming the destination.

In March, the royal palace said he went to Algeria on holiday after the results of medical tests he underwent in the US city of Cleveland were reported as “reassuring.”

He returned to Saudi Arabia from Algeria on April 10.

The advanced age and failing health of the king and of his half-brothers in line to succeed him have raised concerns about the future of the oil giant in the face of the turmoil rocking the Arab world.