Saudi sources said the Pentagon had recently sponsored a secret conference to look at options if the royal family fell. The British Foreign Office believes that the failure of Abdullah's recent Middle East peace plan could have terminally undermined his position. British officials are fearful that Prince Abdullah could face a palace coup from elements within the royal family sympathetic to al Qaeda.

Demonstrations across the kingdom broke out in March, triggered by a fire in a girls' school in which 14 pupils died after the religious police stopped them from escaping. Unrest in the east of the country rapidly escalated into nationwide protests against the royal family that were brutally suppressed by the police.

The tensions between the royal factions will intensify with the death of King Fahd. The condition of the king, in the hospital in Switzerland, is "unstable," doctors said.

British-based Saudi dissident Dr. Saad al-Fagih said: "There is now an undeclared war between the factions in the Saudi royal family."

—Sources: Guardian Unlimited, The Observer.