ABU DHABI — Saudi King Abdullah, the oldest leader in the Arab world, is preparing to undergo surgery. The Saudi royal court said Abdullah, believed to be 95, would be sent to a hospital in Riyad for another back operation.

The court said the surgery was related to two operations the king underwent in 2010.

“In continuation of the scheduled medical followup of King Abdullah, the king will undergo an operation in the coming days in Riyad,” the royal court said on Oct. 11.

In 2010, Abdullah spent three months in the United States and underwent two operations for what was identified as a herniated disc. Since then, much of his authority has shifted to his half-brother, Deputy Prime Minister Prince Nayef Bin Abdul Aziz, also the interior minister.

The royal court did not say why Abdullah would be operated in Saudi Arabia. But Western diplomats said the king was believed to have cut short his convalescence in the United States amid tension within the royal family.

The statement said the forthcoming surgery would seek to relieve back pain. The royal court cited the need to tighten a connector around the king’s third vertebrae.