Riyadh, Jun 17 (PTI): Saudi Crown Prince Nayef bin Abdul Aziz, a half brother of King Abdullah, died today, the royal court said, leaving the oil powerhouse with no apparent successor to the throne.

A long-serving interior minister, Prince Nayef "died outside" Saudi Arabia having recently left the Gulf state for medical treatment, said a statement carried by state media, including Al-Ekhbariyah Television and SPA news agency.

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

The 79-year-old's death, only eight months after he replaced his late brother crown prince Sultan, raises the issue of succession due to the advanced age of the first line of apparent heirs, as turmoil rocks the Arab world.

King Abdullah is 88 and ailing, and nobody is officially in line to replace Nayef.

However, his brother Prince Salman, 76, who took over the portfolio of defence minister after Sultan's death, appears to be a strong candidate.

Nayef, spearheaded Saudi Arabia's clampdown on Al-Qaeda following a wave of attacks in Saudi Arabia between 2003 and 2006, became heir to the throne in October last year.

He 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.

Prince Nayef had been abroad on several occasions this year for medical reasons, including to Algeria, the United States, and Switzerland, where he was shown on television in Geneva three days ago greeting supporters.

The nature of his illness has not been made public.

Less than two weeks ago, his brother Prince Ahmed bin Abdul Aziz 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.