Concerns over succession and distribution of key government positions in Saudi Arabia are rising with octogenarian ruler King Abdullah leaving on Monday for medical treatment in the United States.
His deputy, Crown Prince Sultan, has been abroad for his own health treatment for much of the last two years.
Interior Minister Prince Nayef is poised to step in if anything happens to indispose both Abdullah and Sultan after the king appointed him second deputy prime minister last year -- a move that puts him in a strong position to one day take over.
In order to avoid a power struggle King Abdullah formed an "allegiance council" of sons and grandsons of the kingdom's founder to vote on future kings and their heirs.
Diplomats say it is not clear if the council will kick into action if Abdullah outlives his crown prince. They also say Nayef saw Abdullah's innovation as a snub to keep the conservative security veteran from taking power.
Here are key players of the ruling Al Saud family:
PRINCE NAYEF - Prince Nayef has been interior minister since 1975. He was promoted to second deputy prime minister in 2009 and has since played a more prominent role in public life. Nayef, in his late 70s, chaired cabinet sessions while King Abdullah was on holiday and analysts widely believe he will become crown prince. One of six full-brothers of Sultan, he is seen as a hardliner who might not continue Abdullah's reforms.
PRINCE SALMAN - The governor of Riyadh since 1962, Salman and his family owns a newspaper group including pan-Arab daily Asharq al-Awsat and al-Eqtisadiah. Prince Salman, born in 1936, underwent spine surgery in the U.S. last August and remained outside the kingdom for recuperation. Another full brother of Sultan, he resumes his duties as governor on Tuesday.
PRINCE MUGRIN - The head of Saudi intelligence, Mugrin's public profile has risen in recent years. He organised a conference on combating internet militancy in 2007. Diplomats say he is close to King Abdullah. Born in 1945, he is relatively young but is handicapped in succession by his non-royal mother.
PRINCE MISHAAL - Born in 1926, he was appointed by King Abdullah as chairman of the allegiance council but his public profile is low.
So far no grandsons of Saudi founder Abdul-Aziz have assumed the throne. Here are some of the most prominent:
PRINCE MOHAMMED BIN NAYEF - Son of Interior Minister Prince Nayef who heads Saudi Arabia's anti-terror campaign and is deputy minister of interior. Diplomats say he has won plaudits from Western intelligence agencies for his work combating an al Qaeda campaign to destabilise the kingdom from 2003 to 2006. He survived an assassination attempt in 2009 by a suicide bomber posing as a repentant militant -- an incident that drew favourable attention in Saudi media.
PRINCE KHALED BIN SULTAN - Son of Crown Prince Sultan who led Arab forces during the 1991 war to oust Iraqi forces from Kuwait. He is deputy defence minister and owner of the influential pan-Arab daily newspaper al-Hayat. He led Saudi forces in their war against Yemeni rebels who strayed into Saudi territory last year.
PRINCE ALWALEED BIN TALAL - Entrepreneur businessman and one of the world's richest men, he is the largest individual investor in Citigroup Inc. (C.N). His father's history as a renegade reformer prince who allied with Egypt's President Gamal Abdel-Nasser in the 1960s could hinder his chances of promotion. Islamists also see his pan-Arab entertainment television network Rotana as immoral.
PRINCE KHALED AL-FAISAL - Governor of Mecca province, he is seen as one of the most liberal princes who has eased the religious police's influence in the port city of Jeddah. He is owner of al-Watan newspaper, the country's most liberal daily. A keen poet, his liberal leanings could disqualify him as far as the hardline Wahhabi clerics are concerned.
PRINCE TURKI AL-FAISAL - Born around 1945 and son of King Faisal, he has served as Saudi intelligence chief and as ambassador in London and Washington before retiring in 2006. He is the brother of veteran foreign minister Saud al-Faisal.
PRINCE MITAB - The son of King Abdullah. Last week his father handed him full control of the National Guard, an elite Bedouin corps that handles domestic security -- a move which could set up off a spate of similar transfers of powers to siblings among senior princes keen to preserve their fiefdoms.
PRINCE BANDAR - Born in 1950, this son of Sultan was a famed ambassador to Washington between 1983 and 2005. He is currently Secretary General of the Saudi National Security Council but is thought to have fallen out of favour with Abdullah and other princes over overzealous diplomatic efforts in recent years.