Updated

The Saudi king on Saturday transferred his traditional supervisory duties of the annual Muslim pilgrimage to his deputy prime minister after rupturing a disc in his back.

King Abdullah normally heads the committee charged with ensuring the smooth operation of the hajj, the largest annual gathering in the world. But a statement released by the Royal Court said the 86-year-old monarch herniated a disc in his back and Prince Nayef bin Abdulaziz will take over the supervisory role.

The statement did not say how the king's injury occurred.

More than 2 million people attend the hajj every year. Many Muslims from around the world wait a lifetime for a chance to make the spiritual journey in the footsteps of the Prophet Muhammad and Abraham, whom Muslims view as a forefather of Islam. For believers, it is an opportunity to cleanse one's sins before God.

It is also a logistical nightmare. Over four days, the population of a small city moves by car, bus and foot between Mecca and several holy sites in the desert nearby, each day performing a different rite all at the same time.