Muscat (AFP) - Oman's Sultan Qaboos, who died Friday aged 79, had no children or brothers. His cousins were his closest relatives.
According to the Omani constitution, the royal family shall, within three days of the throne falling vacant, determine the successor.
If the family does not agree on a name, the person chosen by Qaboos in a letter addressed to the royal family will be the successor.
The sultan should be a member of the royal family, as well as "Muslim, mature, rational and the legitimate son of Omani Muslim parents".
Local experts say that there are more than 80 individuals who are legitimate heirs to Qaboos.
Here are the main candidates:
Asad bin Tariq
Asad bin Tariq, 65, whose name is widely assumed in Oman to appear in the sultan's envelope, had been appointed deputy prime minister for international relations and cooperation affairs in 2017. The move was seen as a clear message of support to the sultan's cousin and "special representative" since 2002.
Once commander of the country's armoured brigades, Asad bin Tariq headed governmental delegations in regional and international conferences, received foreign officials, and made several public appearances on behalf of Qaboos.
Haitham and Shihab
Two of Asad's main rivals are also cousins of Sultan Qaboos, Haitham bin Tariq, 65, the heritage and culture minister, and Shihab bin Tariq, 63, who was a close adviser to the sultan.
Haitham, a sports enthusiast, also held the position of undersecretary of the ministry of foreign affairs for political affairs before becoming the minister of heritage and culture in the mid-1990s. He was also the first head of Oman's football federation in the early 80s.
His brother Shihab, former commander of the navy, holds a lower profile, and is mainly tasked with conveying letters to regional leaders, and representing the sultan in high level Arab meetings.
Fahed bin Mahmoud
Fahd bin Mahmoud al-Said, between 75 and 79 years old, is the deputy prime minister for the council of ministers. He is one of the most known and active Omani officials, and a highly entrusted advisor to the sultan.
He took up his position in 1972, two years after the sultan deposed his father in a palace coup, pledging "a new era" for the nation, and has remained in the same position since.
The long serving deputy premier, known for his many public appearances, played on several occasions the role of the prime minister, a position held by Qaboos since he came to the throne.
Taimur bin Asad
A 2007 US diplomatic cable, released by WikiLeaks, pondered the strengths of Asad's 39-year-old son, Taimur, describing him as "personable, affable... (and) markedly overweight but apparently vigorous", according to Foreign Policy magazine.
The cable said Taimur, a second cousin of Sultan Qaboos, is "considered by many Omanis to be the leading candidate in his generation for the succession, particularly if that transition takes place after his father and uncles have passed the age when they would be considered viable successors".
Taimur does not hold any senior official position.
Such a choice would "imitate events" in Qatar, where the 39-year-old Sheikh Tamim bin Hamad is emir, and Saudi Arabia, where the Crown Prince Mohammed bin Salman, 34, will be king.