Thousands of white-robed pilgrims recited Quranic verses from dawn on the 70-meter rocky rise near Mecca, where the Prophet Mohammed is believed to have given his last sermon.

But numbers thinned by midday following official warnings for pilgrims to stay inside between 10 a.m. and 4 p.m..

"I came here early to [avoid] the sun and later I will pray inside my tent," said 54-year-old Adel Ismail, from Syria.

Saudi authorities have taken several steps to reduce the risk from heat at the haj, which has drawn more than 1.6 million pilgrims to one of the world's hottest regions, according to fresh figures published Thursday.

Barring a few years of Covid restrictions from 2020-2022, this haj season has recorded the lowest number of pilgrims in over three decades.

The dip comes after 1,301 people died in temperatures that hit 51.8 degrees Celsius last year -- most of them illegal pilgrims according to Saudi authorities, who implemented stringent measures to reduce their numbers this season.

Unregistered, non-fee paying pilgrims, lack access to the full amenities offered during the haj including air conditioned tents, making them particularly vulnerable to heat-related health risks.

On Thursday, icepacks were handed to people walking towards Mount Arafat, with some placing the small bags on their heads.

With temperatures reaching 42C, officials ushered people away if they spent too long in one place near the bouldered hill, which had fans spraying mist and cool air at its foot.

'I don't think about the sun'

Late Thursday afternoon, pilgrims began making their way to Muzdalifah, halfway between Arafat and the sprawling tent city of Mina, where they will gather pebbles for Friday's symbolic "stoning of the devil".

Despite the heat, they were generally delighted to be performing the haj, one of the five pillars of Islam that must be completed at least once by all Muslims with the means.

"I don't think about the sun or the temperature or anything like that," said Ahmed, a 44-year-old from Egypt.

"Because standing in Arafat is a great thing and a beautiful day, and as you can see, all the pilgrims" are doing it.

Ali, 33, from Pakistan, said he felt "blessed" to take part.

"This is something that I used to see every year on the TV screen during haj and I always thought: 'I wish I could be here'," he said.

Through tears of joy, Iman Abdel Khaleq said she had wanted to perform the haj for 10 years and was overwhelmed with emotion as she arrived at Arafat.

"It's a big dream for me that I had almost given up hope of realizing," the Egyptian woman in her 50s told AFP from the foot of the mount.

High-tech haj

Saudi officials said the heat-mitigation measures implemented this haj had largely been successful in preventing a repeat of last year.

"We are encountering a limited number of heat related illnesses cases this year and this is evidence of the effectiveness of all the organization measures as well as preventive measures," said Mohammed Al-Abd Al-Aali, Saudi Arabia's assistant minister of health.

Ahead of this year's haj, shaded areas have been expanded by 50,000 square meters, thousands more medics are on standby and more than 400 cooling units have been deployed, the haj minister told AFP last week.

Along with the anti-heat measures and thousands of extra personnel, Saudi Arabia is also using an arsenal of high-tech tools to help better manage crowds.

More than 15,000 cameras run through artificial intelligence software are monitoring the holy sites and walkways during an event that has a history of deadly stampedes.

This year, officials have also clamped down hard on unregistered pilgrims looking to sneak into Mecca, using raids, drone surveillance and a barrage of text alerts.

Late Thursday, a haj ministry source said the moves had helped stave off overcrowding at the holy sites so far. 

Haj permits are allocated to countries on a quota basis and distributed to individuals by a lottery.

But even for those who can obtain them, the steep costs prompt many to attempt the haj without a permit, even though they risk arrest and deportation if caught.

Saudi Arabia earns billions of dollars a year from the haj, and the lesser pilgrimage known as umrah, undertaken at other times of the year.