Saudi authorities deployed drones to watch over nearly 2 million pilgrims as they descended Mount Arafat on Sunday and entered the hajj's final stages, part of stepped-up efforts to avoid a repeat of last year's crush amid an escalating war of words with Iran.

Last year, in one of the deadliest disasters to befall the annual Muslim rite in decades, the crush killed nearly 800 pilgrims, according to Riyadh, although counts by countries of repatriated bodies showed over 2,000 people may have died, more than 400 of them Iranians.

On foot or seated on the roofs of buses, the faithful climbed down the craggy hills outside Mecca at sunset and set out en masse for the open plateau of Muzdalifah.