Diplomats from Arab nations on Thursday said hundreds of people had died during this year's Hajj pilgrimage in Saudi Arabia as the faithful faced intense high temperatures at Islamic holy sites in the desert kingdom.

Saudi Arabia has not commented on the death toll amid the heat during the pilgrimage, required of every able Muslim once in their life, nor offered any causes for those who died.

However, hundreds of people had lined up at the Emergency Complex in the Al-Muaisem neighbourhood in Mecca, trying to get information about their missing family members.

Reports were conflicting, but unofficial accounts suggested that at least 500 people had died during the Hajj pilgrimage, with some saying the death toll was likely higher.

Deaths are not uncommon at the Hajj, which has seen at times over two million people travel to Saudi Arabia. There have also been stampedes and epidemics through the pilgrimage’s history.

But the high temperatures and intense heat made things especially treacherous for pilgrims this year, with temperatures hitting 51.8 degrees Celsius in Mecca, Islam's holiest city, on Monday. (Agencies)