The stoning of the three pillars representing the devil is one of the central elements of the annual Hajj pilgrimage, and one that has often been the scene of human tragedy.

The ritual is the final act for pilgrims and takes place in the city of Mina just outside the holy city of Mecca.

Prior to the stoning hundreds of thousands of pilgrims spend the night on the plain of Muzdalifah collecting pebbles in preparation for the rite.

This ritual re-enacts Abraham's pilgrimage to Mecca and requires pilgrims to collect between 49 and 70 pebbles from the ground at Muzdalifah, and throw them at the three pillars at Mina, which represent the devil.

The stoning is the riskiest episode of the Hajj, taking place in an enclosed space that becomes a bottleneck as tens of thousands of pilgrims jostle to make sure their pebbles touch the pillar.

The pillars are located on a large pedestrian bridge, the width of an eight-lane highway, built over the desert plain of Mina.

On the day of Eid-ul-Adha, pilgrims stone the largest of the three pillars with seven stones.

The pillars represent the spot where the devil tried to tempt Abraham not to sacrifice his son Ismael.

For the next three days, pilgrims pelt each of the three stone pillars with seven stones.

The devil is rebuked each time, and the throwing of the stones symbolises those rebukes and the pilgrim's resolve to fight temptation.

This, along with a final circumambulation of the Ka'bah, completes the rituals of the Hajj.

The ritual has a spiritual significance -  by stoning the pillars pilgrims openly declare their enmity to the devil.

After stoning the devil, many male pilgrims will then shave their head; women may cut off a lock of their hair. This is a symbol of rebirth, signifying that their sins have been cleansed by completion of the Hajj.