Muzdalifah: A sea of Muslim pilgrims moved on Wednesday towards the holy site of Muzdalifah in Saudi Arabia, where they gather pebbles for the last major rite of this year's hajj. 

Their symbolic stoning of the devil on Thursday will coincide with the Eid al-Azha feast of sacrifice marked by the world's more than 1.5 billion Muslims.

Around two million white-clad faithful spent a day of prayer Wednesday on a vast Saudi plain and its Mount Arafat for the peak of the hajj pilgrimage.

Police sirens pierced the air and helicopters hovered overhead as the faithful later arrived at nearby Muzdalifah, where water sprays cooled them. They placed prayer rugs and mats on the ground where they will remain until dawn. Many laid down to rest but others savoured tea and refreshments offered by fellow pilgrims.

Most were busy choosing the pebbles they planned to use for the next day's stoning, storing them in empty water bottles.

"We are implementing the Prophet's (PBUH) sunnah by gathering the stones," said Mezian Abdelkarim, 60, of Algeria. The kingdom's authorities have repeatedly warned against the use of political slogans or banners during hajj.

Almost 1.4 million foreign pilgrims are joining hundreds of thousands of Saudis and residents of the kingdom for this year's hajj.