At least 323 Egyptian pilgrims died during the Hajj pilgrimage in western Saudi Arabia, most of them succumbing to heat-related illnesses, two Arab diplomats coordinating their countries' responses told AFP on Tuesday.

"All of them died because of heat" except for one who sustained fatal injuries during a minor crowd crush, one of the diplomats said, adding that the total figure came from the hospital morgue in the Al-Muaisem neighborhood of Mecca.

At least 60 Jordanians also died, the diplomats said, up from an official tally of 41 given earlier on Tuesday by the Jordanian government.

The new deaths bring the total reported so far by various countries to 577, according to an AFP tally. The diplomats said the total at the morgue in Al-Muaisem, one of the biggest in Mecca, was 550.

The Hajj is one of the five pillars of Islam and all Muslims with the means must complete it at least once.

The pilgrimage is increasingly affected by climate change, according to a Saudi study published last month that said temperatures in the area where rituals are performed were rising 0.4 degrees Celsius (0.72 degrees Fahrenheit) each decade.

Around 1.8 million pilgrims took part in the Hajj this year, 1.6 million of them from abroad, according to Saudi authorities.

Each year tens of thousands of pilgrims attempt to perform the Hajj without securing official visas in order to save money, a more dangerous undertaking because these off-the-books pilgrims cannot access air-conditioned facilities provided by Saudi authorities along the Hajj route.

One of the diplomats who spoke to AFP on Tuesday said that the Egyptian death toll was "absolutely" boosted by a large number of unregistered Egyptian pilgrims.

Earlier this month, Saudi officials said they had cleared hundreds of thousands of unregistered pilgrims from Mecca ahead of the Hajj.

Other countries to report deaths during the Hajj this year include Indonesia, Iran and Senegal.