Saudi Arabia says that 1,301 Muslim pilgrims died in the annual Hajj pilgrimage that ended earlier in June amid extreme heat.
Some 83% of the fatalities were unregistered pilgrims, Saudi Health Minister Fahd al-Jalajel said on Sunday without providing a breakdown of their nationalities.
The temperature in the Saudi city of Mecca and other nearby holy sites hovered around 50 degrees Celsius through Tuesday's final pilgrimage day.
"The unregistered pilgrims walked for long distances under the sun without a shelter and rest. A number of them were elderly and some others had chronic diseases," al-Jalajel told the Saudi state television al-Ekhbariya.
The official said the dead had no identification cards, a matter that required time to identify them and contact their families.
Several Arab governments said most of the pilgrims who died in Saudi Arabia, Islam's birthplace, were not registered and had travelled on tourist visas, not the required Hajj visas, which made it harder to find them or determine their actual numbers.
Unregistered pilgrims usually have no access to accommodation and transportation services.
Some 1.8 million pilgrims took part in this year's Hajj. One of the five pillars of Islam, the Hajj is a mandatory duty for all Muslims to complete once in a lifetime, if they have the financial and physical means to do so.