It is Islam's holiest pilgrimage, but the hajj to Makkah in Saudi Arabia has in recent decades been plagued by deadly disasters, from stampedes to militant attacks.

Yet the last time the pilgrimage was cancelled outright was in 1798, when Napoleon Bonaparte invaded Egypt.

The coronavirus pandemic did however force the kingdom to radically downscale the 2020 event to just 10,000 people, a far cry from the 2.5 million believers who took part the previous year.

The number increased last year to reach 60,000 vaccinated Saudi residents, but this year the kingdom is gearing up to host one million Muslims from around the world, taking part in the rituals that start on Wednesday.

Here are some recent incidents that have marred the centuries-old rite:

Stampedes

2015 - A stampede during the "stoning of the devil" ritual in Mina, near Makkah, kills up to 2,300 worshippers on September 24, in the worst hajj disaster ever.

That comes after more than 100 people are killed and hundreds injured, including many foreigners, when stormy weather topples a crane onto Makkah's Grand Mosque less than two weeks before the pilgrimage.

2006 - Some 364 pilgrims die in a stampede on January 12 during the Mina stoning ritual, in which hajj participants throw pebbles at three headstones to symbolise their rejection of Satan.

This follows a hotel collapse a week earlier in the city centre, which kills 76 people.

The previous year, three pilgrims are crushed to death in a stampede on January 22 at the stoning ceremony.

2004 - 251 people die after a huge stampede at the stoning ceremony on February 1.

1998 - More than 118 people are killed and 180 injured in a stampede in Mina on April 9.

1994 - During the Mina stoning on May 24, a stampede kills 270 people, with authorities blaming "record numbers" of pilgrims.

1990 - The failure of a tunnel ventilation system triggers a huge stampede on July 2 that kills 1,426 pilgrims, mainly from Asia.

Attacks

1989 - A twin attack on the outside of the Grand Mosque on July 10 kills one and wounds 16. Weeks later, 16 Kuwaiti Shiites are found guilty and executed.

1979 - Hundreds of gunmen calling for the abdication of the Saudi royal family barricade themselves inside Makkah's Grand Mosque on November 20, taking dozens of pilgrims hostage. The official toll of the assault and subsequent fighting is 153 dead and 560 wounded.

Protests

1987 - Saudi security forces suppress an unauthorised protest by Iranian pilgrims on July 31 in which more than 400 people including 275 Iranians are killed, according to an official toll.

Infernos

1997 - A fire on April 15 caused by a gas stove rips through a camp housing pilgrims at Mina, killing 343 and injuring around 1,500.

1995 - Three people die and 99 are injured on May 7 in a fire at the Mina camp.

1975 - A huge fire on December 14 started by an exploding gas canister in a pilgrim camp close to Makkah kills 200 people.