|Members of the royal family carried the deceased crown prince's body into Imam Turki bin Abdullah Mosque [AFP]
Saudi Arabian royals and visiting dignitaries have mourned the death of Crown Prince Sultan bin Abdulaziz Al Saud after the body of the former heir to the Gulf kingdom's throne arrived in the capital Riyadh.
Sultan's funeral began before the afternoon prayer on Tuesday, and his body will then be taken away for burial.
The funeral sets the stage for an eventual generational shift in the ageing leadership of the world's top oil exporter, even if Saudi King Abdullah bin Abdulaziz Al Saud picks Prince Nayef bin Abdul-Aziz, 77, to succeed him.
Hundreds of men, including the king, gathered on an airport runway to watch as the coffin of the 83-year-old prince who died of colon cancer in New York on Saturdaywas flown back to Riyadh on Monday.
Sultan was the seventh of the 36 sons of King Abdul-Aziz bin Saud, who united and founded Saudi Arabia in 1932.
The question of succession will be decided by the Allegiance Council, comprising House of Saud princes
Like the deceased king Fahd, he was a member of the "Sudairi Seven", the powerful alliance of seven surviving sons of Abdulaziz and one of his wives, Princess Hissa al-Sudairi.
Sultan served as defence minister for nearly 50 years, the longest term of any Saudi minister, and brought advanced military hardware to the kingdom from the US and UK.
Among his sons are Prince Khalid, who has overseen fighting against Yemeni rebels and commanded Arab forces against Saddam Hussein in the first Gulf War, and Prince Bandar, who served as ambassador to the US between 1983 and 2005.
With Sultan's death, his brother Nayef, the longtime minister of interior, becomes the most probable candidate to be next in line to rule after Abdullah.
Abdullah's choice to replace Sultan may signal how the conservative Islamic state manages the transition to its future leaders.
In 2006, the king formed an Allegiance Council meant to help oversee succession issues. The king has ultimate authority to choose the next crown prince and heir, and it remains unclear how exactly the council will interact with him.
Abdullah, Sultan and Nayef have run the country since the late King Fahd fell ill in 1995, but the monarch is in his late 80s and has spent three months abroad this year recovering from a back problem that again required surgery last week.
He remains firmly in control of the kingdom, but the focus will increasingly fall on Nayef and some younger princes.
Chief among them is Prince Salman, the Riyadh governor who is a full brother of Sultan and Nayef and is seen as next most important in a ruling family that has prized seniority since it was founded by Abdulaziz Ibn Saud in 1932.