Robed worshippers arrived on buses or on foot, many shaded by umbrellas, at the vast encampment in Mina after performing the "tawaf" -- walking seven times around the Kaaba, the giant black cube at Mecca's Grand Mosque.

Chanting "God is great" and "God, we answer your call", many were awash with spiritual fervor as they followed in the footsteps of the Prophet Mohammed's final pilgrimage nearly 1,400 years ago.

Participants, who numbered 1.5 million by Monday, have travelled from all parts of the world for the annual rites, this year held in intense heat with forecast daily highs of 44 degrees Celsius.

"It's very, very hot," said Fahad Azmar, 31, from Pakistan. "But I thank God for the opportunity to be here."

They are spending the night at Mina, a rocky valley several kilometers outside Mecca, before climbing Mount Arafat for the pilgrimage's climax on Saturday.

Accommodation in Mina's air-conditioned tents is organized by nationality and price, depending on how much each pilgrim paid for their haj package.

Many worshippers were tightly packed inside as they sat and lay on narrow mattresses laid close to each other on the floor.

"There should be more space between the beds, and the air-conditioning doesn't work very well... but the haj is all about patience," said Intisham al-Ahi, a 44-year-old Pakistani who was sharing a tent with dozens of his compatriots.

Elsewhere, a group of Moroccan pilgrims was growing angry, claiming to have been given a raw deal by the agent who booked their pilgrimage.

"There's more people than are allowed in the tents... they're asking us to share tents with people who paid half of what we spent," fumed Hicham, who did not want to give his surname. He said he paid about 17,000 euros for his trip.

'Carry an umbrella' 

Outside, misting stations were installed to cool the faithful, and security guards splashed passers-by with water.

Most of the haj is outdoors but Saturday will be particularly testing for the worshippers, when they spend most of the day praying on Mount Arafat.

Mohammed al-Abdulali, spokesperson for the Saudi health ministry, told AFP this week there were more than 10,000 documented cases of heat-related illnesses last year, 10 percent of which were heat stroke.

A text message sent to pilgrims on Thursday instructed them to "drink water regularly, more than two liters daily" and to "always carry an umbrella", warning that temperatures could climb to 48 degrees Celsius.

Many pilgrims said they would pray for Palestinians in the Gaza Strip, more than eight months into the Israel-Hamas war that has left tens of thousands dead.

Zahra Benizahra, 78, from Morocco could not hold back her tears as she described the "images of war, displaced people, dead children" that haunt her.

"Our brothers are dying, and we can see it with our own eyes," she told AFP.

Belinda Elham of Indonesia, which has the world's largest Muslim population, said she would "pray every day so that what's happening in Palestine ends".

Palestinian pilgrims

The Gaza war was triggered by Hamas's unprecedented attack on southern Israel on October 7, which resulted in the deaths of 1,194 people, mostly civilians, according to an AFP tally based on Israeli official figures.

The militants also seized 251 hostages. Of these, 116 remain in Gaza although the army says 41 of them are dead.

Israel's retaliatory offensive against Hamas has killed at least 37,232 people, also mostly civilians, according to the Hamas-ruled territory's health ministry.

Some 2,000 Palestinians are performing the haj at the special invitation of King Salman, official media said.

However, the Gulf kingdom's minister in charge of religious pilgrimages warned last week that "no political activity" will be tolerated.

The haj, one of the world's largest religious gatherings, is one of the five pillars of Islam and must be performed at least once by all Muslims who have the means to do so.

Some have waited for years for the chance to make the trip, with permits allocated by Saudi authorities on a quota basis for each country.

Last year's haj drew more than 1.8 million pilgrims, according to official figures, after authorities lifted pandemic-era restrictions and scrapped age limits.