Saudi Arabia’s King Abdullah has been hospitalized in the capital Riyadh to undergo a back surgery for the third time within a year

Saudi Arabia's King Abdullah has been hospitalized in the capital Riyadh to undergo a back surgery for the third time within a year.

The monarch arrived at the King Abdul-Aziz Medical City in Riyadh on Sunday evening to undergo a surgery to tighten the connectors around his third vertebra, Xinhua reported, citing the Saudi Arabia's official news agency.

In November 2010, the Saudi king had two other back surgeries in New York City to treat a herniated disc and a blood clot pressing on nerves in his back, according to official explanations.

The king's half-brother, Crown Prince Sultan bin Abdul-Aziz, took control of the kingdom when King Abdullah was in the US.

The crown prince has been abroad for much of the past two years receiving treatment for what is believed to be cancer.

The next-in-line after King Abdullah is widely assumed to be Prince Nayef, who has a reputation of being more conservative than his elder brothers, the king and the crown prince.

In Saudi Arabia, the line of succession does not move directly from father to eldest son, but has moved down a line of brothers born to the kingdom's founder Ibn Saud, who died in 1953.