The Saudi royal palace on Saturday announced the death of Crown Prince Sultan bin Abdul Aziz, national television reported.
Prince Sultan, who was 80 according to government records, had been on a visit to the United States for medical tests. As well as heir to the throne of the world's top oil exporter, he had been defense minister and minister of aviation for about four decades.
“With deep sorrow and sadness the Custodian of the Two Holy Mosques King Abdullah bin Abdulaziz mourns the death of his brother and his Crown Prince Sultan... who died at dawn this morning Saturday outside the kingdom following an illness,” SPA, the state news agency said.
Saudi television broke its schedules early on Saturday to broadcast Koranic verses accompanied by footage of the Kaaba in Mecca, Islam’s holiest site.
The Crown Prince left to New York for medical checks in June this year, making it the second time he enters the hospital there in the past three years. He died at dawn Saturday, Saudi time, and his burial ceremony will take place on Tuesday in Riyad.
U.S. President Barack Obama offered condolences to Saudi Arabia after the death of Crown Prince Sultan, calling him a “valued friend” who helped cement ties between the allies.
“He was a strong supporter of the deep and enduring partnership between our two countries forged almost seven decades ago,” Obama said in a statement, adding that he learned of the crown prince's death with “great regret.”
“As minister of defense and aviation for almost 50 years, Crown Prince Sultan dedicated himself to the welfare and security of his people and country and was a valued friend of the United States,” Obama said.
“On behalf of the American people, I extend my deepest condolences to King Abdullah, the royal family, and the people of Saudi Arabia.”
Prince Sultan, born in 1931, was the 15th son of Saudi King Abdul-Aziz.
In 2009, he spent several months at New York Presbyterian Hospital where he underwent more surgery and then went for recovery to Agadir, Morocco.
He has spent much of last year in medical treatment.
Prince Sultan who was half brother of the kingdoms current ruler, King Abdullah, was also known for his charity work, administrative reforms and sending Saudi students abroad to study.
He brokered the Saudi-Yemeni deal over border disputes six years ago.
Widely thought to be next in line after Sultan is Interior Minister Prince Nayef, who was named second-deputy prime minister in 2009.
Unlike in European monarchies, the line of succession does not move directly from father to eldest son, but has moved down a line of brothers born to the kingdom’s founder Ibn Saud, who died in 1953.
Anyone who rises to the throne is likely to maintain the kingdom’s close alliance with the United States. But there could be internal differences. King Abdullah has been seen as a reformer, making incremental changes to improve the position of women, for example, and to modernize the kingdom despite some backlash from ultra-conservative clerics.