JEDDAH, SAUDI ARABIA // Saudi Arabia's Crown Prince Sultan bin Abdulaziz Al Saud died yesterday in New York, where he had been receiving medical treatment.
In a statement, the Saudi royal court said: "It is with deep sorrow and grief that the Custodian of the Two Holy Mosques King Abdullah bin Abdulaziz Al Saud mourns the loss of his brother and Crown Prince His Royal Highness Prince Sultan Abdulaziz Al Saud."
The statement, which was carried on the official Saudi Press Agency, added that Prince Sultan's funeral will be held on Tuesday afternoon in Riyadh at the Imam Turki bin Abdullah mosque.
Sheikh Khalifa, President of the UAE, conveyed his condolences to King Abdullah and the Saudi people and declared three days of mourning, during which flags will fly at half-mast at all UAE government institutions.
Sheikh Mohammed bin Rashid, Vice President of the UAE and Ruler of Dubai, and Sheikh Mohammed bin Zayed, Crown Prince of Abu Dhabi and Deputy Supreme Commander of the Armed Forces, also sent their condolences.
Prince Sultan, 85, was the half-brother of King Abdullah, who is two years older than him.
Prince Sultan, who was the kingdom's deputy prime minister and the minister of defence and aviation, had suffered what was widely believed to have been cancer for a number of years. He underwent surgery in New York in February 2009 for an undisclosed illness and spent nearly a year abroad, recuperating in the United States and at a palace in Agadir, Morocco.
The most likely candidate to replace Prince Sultan as King Abdullah's designated successor is Prince Naif, 77, who as interior minister is in charge of internal security forces.
After Prince Sultan fell ill in 2009, King Abdullah appointed Prince Naif - also his half-brother - second deputy prime minister, traditionally the post of the second in line to the throne.
King Abdullah is now expected to call to session the Allegiance Council to appoint the new crown prince. The Allegiance Council was set up in 2006 soon after King Abdullah became monarch, and is encharged with voting to approve the king's choice of crown prince or nominating its own choice instead.
"The succession will be orderly," Asaad Al Shamlan, a professor of political science in Riyadh, told Arab News. "The point of reference will be the ruling of the Allegiance Council. It seems to me most likely Naif will be chosen. If he becomes crown prince, I don't expect much immediate change."
News of Prince Sultan's death prompted all Saudi state television channels to cancel regular programming and go live to shots from the mosque in Mecca.
Schools were closed early as Saudis reacted to the news of the crown prince's death.
"When I got to the office this morning, I saw many of my colleagues had changed their phone's screensaver picture to show Prince Sultan's image," said Abdullah Al Toaimi, 29, a Saudi Airlines employee. "The mood at the office was sombre. Everybody was offering condolences to everyone else. Many were teary-eyed. This is a sad day for Saudi Arabia. May Allah have mercy on his soul; he was a great man."
Barack Obama, the US president, called the prince a "valued friend" who had helped cement ties between the allies.
Hillary Clinton, the US secretary of state, emphasised Washington's enduring ties with the kingdom and said Prince Sultan would be missed.
Saudi Arabia has been ruled since 1953 by the sons of its founder, King Abdulaziz, who had more than 40 sons by multiple wives. Whereas King Abdullah has been seen as a reformer - for example, making cautious changes to improve the position of women, such as granting them the right to vote in elections scheduled for 2015 - Prince Naif has been seen as more conservative and closer to the clerics.
With his six brothers, Prince Sultan made up the powerful "Sudairi Seven" faction of sons of king Abdulaziz - all half-brothers of King Abdullah - by a favourite wife, Princess Hassa Al Sudairi.
Prince Sultan was educated in the royal court and was clearly on the rise when named governor of Riyadh in 1947. Over the next decade he served as agriculture minister and then communications minister. King Faisal named him to the defence portfolio in 1962, and he became one of a handful of key princes, including the future King Abdullah and Prince Sultan's full brothers Prince Naif and Prince Salman, who have run Saudi Arabia for four decades.
Robert Lacey, author of The Kingdom, a book on the Al Saud dynasty, described the tall, well-built Prince Sultan as someone who "works and plays hard".
As defence and aviation minister, and the government's inspector general, Prince Sultan oversaw a major build-up of the kingdom's armed forces and the national carrier Saudi Arabian Airlines.
He presided over a military assault on the Grand Mosque in Mecca after Islamist extremists had seized it in 1979.
A series of deals to build up the air force through the arms dealer Adnan Khashoggi in the 1970s and then through Prince Sultan's son Prince Bandar in the 1980s - notably the Yamamah deals with Britain's BAE - were embroiled in allegations of corruption abroad.
Although Prince Sultan at first resisted the idea of allowing US troops to mount an attack from Saudi soil after Saddam Hussein's invasion of Kuwait in 1990, his cooperation was essential in the US-led Desert Storm campaign in 1991.
The same was true in the US-led invasion of Iraq of 2003, when US air command operations, aircraft and some troops were stationed in the airbase south of Riyadh that bears his name.
The Saudi side of Desert Storm was led by Prince Sultan's son Prince Khalid, who was then named assistant defence minister in 2001.
His son Bandar was in charge of the kingdom's ties with the United States as ambassador from 1983 to 2005, crafting a close relationship especially with the family of the then-president George W Bush.
* With additional reporting by Agence France-Presse, Associated Press and Reuters