Saudi Arabia's royal palace says King Abdullah will undergo new back surgery in the capital, Riyadh, in the coming days, following two similar operations last year in the United States.

Details of the planned procedure, announced Tuesday, were not disclosed.

The health of the ruler of the world's leading oil exporter is closely followed, given his age and the concentration of power among Saudi Arabia's ruling royal family. The king is thought to be in his late 80s.

King Abdullah was absent for three months late in 2010 while he underwent treatment in New York for a herniated disc that caused blood to accumulate around his spine. That surgery and a second, follow-up procedure were declared successful.

During the king's stay in the U.S. and his convalescence in Morocco, his brother – Crown Prince Sultan – was in charge of governing the kingdom.