Saudi King has successful back operation-royal court

RIYADH Nov 18 (Reuters) - Saudi Arabia's King Abdullah has undergone successful back surgery at a hospital in the capital, Riyadh, to tighten a loose ligament, the royal court said in a statement carried by state media on Sunday.

The stability of Saudi Arabia, the world's largest oil exporter and a key U.S. ally, is of global concern. The kingdom holds more than a fifth of world crude reserves and is the birthplace of Islam.

"A surgery was performed on the Custodian of the Two Holy Mosques, King Abdullah bin Abdulaziz, at the National Guard's King Abdulaziz Medical City in Riyadh on Saturday ... where a loose ligament in the upper back was tightened," the statement, carried on state television and the SPA news agency, said.

"With God's help, the surgery ended at 0315 on Sunday morning ... and thanks be to God it was successful," it added in Arabic.