More than one million Muslim pilgrims streamed into a giant tented city near Mecca, Saudi Arabia, under a scorching sun on Friday as the hajj pilgrimage got underway against the grim backdrop of the Gaza war.

Robed worshippers arrived on buses or on foot, many shaded by umbrellas, at the vast encampment 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 fervour 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 sweltering conditions with forecast daily highs of 44 degrees Celsius (111 Fahrenheit).

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

They will spend the night at Mina, a rocky valley several kilometres (miles) outside Mecca, before climbing Mount Arafat for the pilgrimage's climax on Saturday.

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

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

- 'Carry an umbrella' -

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

Most of the hajj 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 litres 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 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 in response has carried out a military offensive in Gaza that has left at least 37,232 people dead, also mostly civilians, according to the health ministry in the Hamas-ruled territory.

Some 2,000 Palestinians are conducting the hajj 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 hajj, 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.

Nonaartina Hajipaoli, 50, told AFP she felt privileged to be among the 1,000 pilgrims who came this year from Brunei in Southeast Asia.

"I'm speechless, I can't describe what I feel," she said.

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