Saudi Arabia's Crown Prince Sultan has died, the royal court said on Saturday, and Interior Minister and reputed conservative Prince Nayef was expected to become the new heir to the throne in the world's biggest oil exporter.
NBC News reported that Sultan died at a hospital in New York City. He is expected to be buried Tuesday in Riyadh.
Sultan, whose age was officially given as 80 and who died in New York of colon cancer early on Saturday Saudi time, had been a central figure in Saudi decision-making since becoming defense minister in 1962 and was made crown prince in 2005.
Saudi analysts predicted an orderly transition at a time when much of the Middle East is in turmoil after mass uprisings against autocratic leaders by citizens demanding democracy.
Saudi King Abdullah reacted to the "Arab Spring" by ordering spending of $130 billion on social benefits, housing and jobs, but he and his new crown prince face challenges from al Qaeda militants, a restless Shi'ite minority and civil conflict in neighboring Yemen.
Saudi Arabia is also locked in a confrontation with Shi'ite Muslim power Iran, accused by the United States of plotting to kill the kingdom's ambassador to Washington.
Earlier this month, the Saudi Interior Ministry accused an unnamed foreign power, widely assumed to mean Iran, of instigating protests by the Saudi Shi'ite minority in which 14 people, including 11 security officers, were injured.
'A strong leader' Sultan, who was the oil-rich kingdom's deputy prime minister, had been defense minister and minister of aviation for about four decades.
"With grief, King Abdullah bin Abdel Aziz mourns the death of Sultan bin Abdel Aziz Al Saud, crown prince and his brother," the palace said in a statement.
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 was a strong leader and a good friend to the United States over many years as well as a tireless champion for his country. He will be missed," said U.S. Secretary of State Hillary Clinton during a visit to Tajikistan. "Our relationship with Saudi Arabia is strong and enduring and we will look forward to working with the leadership for many years to come."
Sultan was the kingdom's defense minister in 1990 when U.S. forces deployed in Saudi Arabia to defend it against Iraqi forces that had overrun Kuwait. His son, Prince Khaled, served as the top Arab commander in the 1991 operation Desert Storm, in which U.S.-led troops drove the Iraqis out of Kuwait.
Sultan is survived by 32 children from multiple wives. They include Bandar, the former ambassador to the United States who now heads the National Security Council, and Khaled, Sultan's assistant in the Defense Ministry.
Britain's foreign secretary, William Hague, said Sultan served his country with "great dignity and dedication."
Saudi Arabia has been ruled since 1953 by the sons of its founder, King Abdul-Aziz, who had more than 40 sons by multiple wives. Sultan was part of the aging second generation of Abdul-Aziz's sons, including Nayef, the full brother of the late King Fahd, who died in 2005.
Sultan seeks medical treatment
Sultan underwent surgery in New York in February 2009 and spent nearly a year abroad recuperating in the United States and at a palace in Agadir, Morocco. According to a leaked U.S. diplomatic cable from January 2010, Sultan had been receiving treatment for colon cancer since 2009.
Sultan oversaw a defense spending spree which made the kingdom one of the world's biggest arms buyers.
Sultan had an intestinal cyst removed in 2005 and had spent several months abroad for treatment and recreation.
While Saudi Arabia insisted he was fully cured, diplomats in Riyadh said he gradually retreated from participating in decision-making and often worked only for one or two hours a day.
Many of his duties had been informally shifted to other princes, most notably to his son Khaled who led Saudi and Arab forces during the 1991 war to remove Saddam Hussein's Iraqi army from Kuwait. Prince Khaled, who is assistant defense minister, is also the owner of influential pan-Arab daily al-Hayat.
While defense minister, Sultan spent hundreds of billions to modernize the forces of the country where Islam was born 1400 years ago, doubling the regular armed forces to more than 100,000 men and buying advanced weapons from all over the world.
Born in Riyadh, Sultan was educated by private tutors and spoke some English. He also went to a school for princes.
He was keen to maintain close ties with the West, especially the United States, though like the rest of the royal family he distanced himself from the U.S.-led attack on Iraq in 2003.
The most likely candidate for the throne after Sultan is Prince Nayef, the powerful interior minister in charge of internal security forces. After Sultan fell ill, the king gave Nayef an implicit nod in 2009 by naming him second deputy prime minister, traditionally the post of the third in line.
Abdullah is aged in his late 80s and underwent back surgery earlier this month but has been pictured since then in apparently good health.
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.