A view of the camp city at Mina, near the holy city of Mecca September 24, 2015.[Photo/Agencies]

Other images showed bodies of men in white hajj garments piled on top of each other. Some corpses bore visible injuries.

Unverified video posted on Twitter showed pilgrims and rescue workers trying to revive some victims.

The hajj, the world's largest annual gathering of people, has been the scene of numerous deadly stampedes, fires and riots in the past, but their frequency has been greatly reduced in recent years as the government spent billions of dollars upgrading and expanding hajj infrastructure and crowd control technology.

Safety during hajj is a politically sensitive issue for the kingdom's ruling Al Saud dynasty, which presents itself internationally as the guardian of orthodox Islam and custodian of its holiest places in Mecca and Medina.