Tens of thousands of Muslim pilgrims clambered up rocks and nestled between boulders on Thursday as they embarked on a day of worship under a scorching sun at the Hajj in Saudi Arabia.

Pilgrims were set to perform the last major ritual of the hajj -- the "stoning of the devil" -- on Friday, as Muslims around the globe celebrated the beginning of the Eid al-Adha holiday.

Large numbers of Muslims converge once a year on Saudi Arabia to unite in a series of religious rituals and acts of worship as they perform the Hajj, the pilgrimage that is one of the pillars of Islam.