Vast crowds of robed worshippers hurled pebbles in the "stoning of the devil" ritual on Wednesday as the biggest hajj pilgrimage since the start of the pandemic draws to a close in intense Saudi Arabian heat.

From dawn in Mina, hundreds of thousands of Muslim pilgrims began pelting three concrete monoliths representing Satan, and heading to Mecca for a final "tawaf" -- walking in circles around the Kaaba, the giant black cube at the Grand Mosque.

More than 1.8 million people are taking part in the first unrestricted hajj since Covid struck in 2020. About 2.5 million, the most on record, joined the pilgrimage in pre-pandemic 2019.

As well as crowds at every turn, the visitors have had to contend with ferocious temperatures at the hajj, which currently coincides with the Saudi summer.

Temperatures peaked at 48 degrees Celsius (118 Fahrenheit) on Tuesday, when the pilgrims prayed for hours at Mount Arafat, and were expected to hit 47 degrees on Wednesday in Mina.

"I will not think of doing hajj again until it takes place in winter," said Farah, a 26-year-old Tunisian who did not want to give her full name.

"My body is melting," she said.

As helicopters buzzed overhead, pilgrims flooded the streets around Mina. In Mecca, the Grand Mosque was packed from the early morning with circling pilgrims, who loudly congratulated each other on completing the rituals.

- Deadly history -

This year's attendance figure, announced by Saudi officials on Tuesday, falls well short of their predictions of beating the 2019 record, possibly because of the heat or the cost, at around $5,000 per person just to attend.

The overwhelming majority of the 1.8 million pilgrims -- more than 1.6 million -- are foreigners, coming from about 160 countries.

The hajj is a major revenue-earner for Saudi Arabia, which is trying to pivot its oil-reliant economy in new directions including tourism. The kingdom makes an estimated $12 billion a year from the hajj and year-round umrah pilgrimages.

Saudi Arabia's King Salman issued a message wishing "wellbeing and prosperity on our country, on Muslims and the world" and announced he would pay for sacrificial animals for nearly 5,000 of the poorest pilgrims.

Wednesday's devil-stoning marks the start of the three-day Eid al-Adha holiday, celebrated by Muslims by buying and slaughtering livestock to commemorate Abraham's willingness to sacrifice his son.

Mina's walkways have proven deadly in the past: in 2015, a stampede killed up to 2,300 worshippers in the worst hajj disaster ever. A similar incident killed 364 in 2006.

Other stampedes were reported in 2004, 1998 and 1994. In 1990, the failure of a tunnel ventilation system triggered a huge rush that killed 1,426 pilgrims, mainly from Asia.

There have been no major incidents since 2015, and the site has been extensively remodelled with a multi-storey bridge to allow the pilgrims to access the monoliths safely.

- 'Very exhausted' -

The scorching conditions have been perhaps the biggest challenge for this year's worshippers, including many elderly after a maximum age limit was scrapped.

In recent years the hajj, which follows the lunar calendar, has fallen in the Saudi summer, at a time when global warming is making the desert climate even hotter.

Experts have warned that temperatures of 50 degrees Celsius could become an annual occurrence in Saudi Arabia by the end of the century.

As protection from the heat, many pilgrims have been walking with umbrellas to shield themselves from the sun, while others carry their folded prayer blankets above their heads.

One security guard was seen fanning a seated pilgrim, apparently overcome by the heat at Mina. According to official figures, at least 287 people have been treated for heat exhaustion and heatstroke.

On his way out of Arafat on Tuesday, Sobhi Saeed, a 56-year-old Egyptian, said he was fulfilled but drained as the hajj winds down.

"I am very exhausted. I feel very dehydrated."

The rituals started on Sunday at Mecca's Grand Mosque, Islam's holiest site, before an overnight stay in tents and then the prayers on Mount Arafat, where the Prophet Mohammed is believed to have delivered his final sermon.

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