RIYADH: Saudi Crown prince Sultan bin Abdul Aziz has returned to the kingdom from Morocco as King Abdullah prepares to leave for the United States for treatment of back ailment, SPA news agency reported Monday.

Sultan, who has spent nearly 12 weeks at his palace in Agadir, returned on Sunday, according to SPA. He will take up the reins during Abdullah’s absence.

Sultan, 85, who has served as defence minister for the past five decades, has himself been receiving treatment for the past two years for what analysts and diplomats believe to be cancer.

King Abdullah, 86, is due to depart later Monday to the United States for treatment of a herniated disc and blood accumulation around the spine, a painful but treatable spinal ailment.

Abdullah, king since 2005, had reduced his duties since June this year over health problems which were never previously officially disclosed.

Health Minister Abdullah al-Rabeeah told state television late Sunday that the monarch was “in a stable state and is well.”

He will “undergo further medical examination and continued treatment ... at a centre specialising in spinal problems” in the United States, the minister said.

Any transfer of power in the absolute monarchy, founded in 1932, is keenly watched by oil markets as the OPEC kingpin has the largest proven crude reserves with over 260 billion barrels.

It is the leading oil exporter, pumping about 8.2 million barrels per day.

The Saudi royals who have dominated the government for 30 years or more are all aged and have been treated for various health problems, usually never defined, during the past year.

Prince Nayef, 76, Sultan’s full brother and considered second in line to the throne, has also had unspecified treatment in the past 12 months. He has been interior minister for 35 years. — AFP