Two witnesses told The Independent that pilgrims were moving in two directions, when chaos ensued. "People were climbing over one another just to breathe. It was like a wave. You go forward and suddenly you go back," said Abdullah Lotfy. Another woman told reporters she was returning from the Jamarat and met up with her husband, who was heading towards the Jamarat, when people began pushing and falling to the ground. "I was about to die," she said. Iran's Supreme Leader, Ayatollah Ali Khamenei, blamed mismanagement by Saudi Arabian authorities for the stampede, which killed at least 90 Iranians. Iran's Haj organisation said the closure of two paths near the site of a symbolic stoning of the devil had caused the crush. Said Ohadi, head of the organisation, said the paths had been closed for "unknown reasons" but this left only three routes to the area where the stoning ceremony is held in Mina. He told state television: "Today's events show mismanagement and lack of serious attention to the safety of pilgrims. There is no other explanation. The Saudi officials should be held accountable." Hundreds of thousands of Muslim pilgrims make their way to cast stones at a pillar symbolising the stoning of Satan, in a ritual called 'Jamarat,' the last rite of the annual Haj, in Mina near the holy city of Mecca, Saudi Arabia. Credit:AP A crowd safety and risk analysis specialist, G. Keith Still, told The Washington Post the deaths appeared to have occurred as the result of these groups of people moving in two directions, creating a compression, a dangerous situation that can be further fuelled by panic. Previous research has found many who die in so-called stampedes are not trampled to death but rather suffocate while standing, unable to breathe. As in some previous incidents, the Saudi government has already moved to lay some of the blame with the crowds, with Health Minister Khalid al-Falih saying the deaths were "possibly caused by the movement of some pilgrims who didn't follow the guidelines and instructions issued by the responsible authorities".

"However, this is God's will," he said in another interview. Why do Muslims make this journey to Mecca? Undertaking a Haj to Mecca at least once in your lifetime is a duty for all Muslims who are physically and financially able to do so, and a deeply significant spiritual experience. Muslim pilgrims pray on a rocky hill called the Mountain of Mercy, near the holy city of Mecca, where the prophet Muhammad is believed to have delivered his last sermon nearly 1400 years ago. Credit:AP Pilgrims flock to the ancient city for a five-day period during the last month of the Islamic lunar calendar. While there, they wear wear white garments, and perform a series of rites to reenact the Prophet Muhammad's own journey and actions.

It is the largest annual pilgrimage on Earth and numbers continue to grow. While once a difficult and perilous journey in and of itself, the ease of modern travel has made it increasingly possible for Muslims from all parts of the world to visit Mecca, from around 100,000 people in the late 1920s, to crowds of between 2 and 3 million people today. Emergency workers and pilgrims to Mecca gather around those crushed in the stampede in Mina, Saudi Arabia. Credit:AP Haven't mass casualties happened before? The Haj has been marred by numerous terrible tragedies over the years, many caused by surging crowds in confined spaces or fires, claiming the lives of thousands of pilgrims in the last three decades. These include: In 1990 , more than 1400 people were crushed or suffocated to death in a pedestrian tunnel, in the worst incident in recent memory. More than 500 of those killed were Indonesians, and the numbers of overall victims were so high, they had to be buried in a mass grave.

, more than people were crushed or suffocated to death in a pedestrian tunnel, in the worst incident in recent memory. More than 500 of those killed were Indonesians, and the numbers of overall victims were so high, they had to be buried in a mass grave. In 1994 , more than 250 people were killed in a crush as a crowd surged forward on narrow pedestrian paths while trying to perform a symbolic ritual where stones are thrown at pillars representing the devil.

, more than people were killed in a crush as a crowd surged forward on narrow pedestrian paths while trying to perform a symbolic ritual where stones are thrown at pillars representing the devil. In 1997 , more than 200 people died when a fire broke in a sea of tents where pilgrims were staying.

, more than people died when a fire broke in a sea of tents where pilgrims were staying. In 1998 , a further 118 people died in a similar surge during the stoning ritual, this time many people also fell to their death from a bridge.

, a further people died in a similar surge during the stoning ritual, this time many people also fell to their death from a bridge. In 2004 , around 250 people were crushed and killed, again during the stoning ritual.

, around people were crushed and killed, again during the stoning ritual. In 2006, at least 346 people died in a chaotic surge, which some witnesses blamed on police trying to block some entrances and authorities blamed on "unruly pilgrims".

Why do these disasters continue to occur? The enormous and ever-growing numbers of people travelling to Mecca each year presents a logistical nightmare for authorities. The Haj must be performed at a fixed time, and the rites must be carried out in the same sequence, and often in extremely hot weather, making diffusing the crowds and ensuring safety difficult. Abraj Al-Bait Towers with the four-faced clocks stands over the Grand Mosque, where a crane collapsed earlier in September killing dozens. File photo. Credit:AP In the wake of many previous disasters, the Saudi government has announced and carried out new works to try to improve safety, upgrade infrastructure and amend regulations, with spending exceeding $300 billion since 1992, according to one research paper. Past measures include redesigning the Jamarat Bridge, deploying tens of thousands of stewards and troops to monitor crowds, expanding walkways and ramps to allow more people to move towards significant sites and replacing tents with permanent fibreglass installations. There is some attempt to control numbers, too. Countries have quotas of how many of its citizens may take part - The Jakarta Globe reported there was a 17-year waiting list in some regions of Indonesia.

A rescue worker attends to a man injured in the stampede in Mina, Saudi Arabia. Credit:AP But however important these measures may be, they have been demonstrably insufficient to prevent ongoing mass casualties, and ensure the safe movement of the crowds around the area. In the wake of the latest calamity, questions are being asked about what else must be done to prevent further deaths, including dramatically reducing the numbers of pilgrims allowing to take part in the Haj each year. So far, the Saudi King Salman has ordered a safety review and conceded there was a need "to improve the level of organisation and management of movement" of pilgrims. A Muslim pilgrim prays on a rocky hill called the 'Mountain of Mercy,' on the Plain of Arafat, near the holy city of Mecca, Saudi Arabia. Credit:AP



Australians with concerns for the welfare of family and friends in the Haj should call the Department of Foreign Affairs and Trade 24 hour Consular Emergency Centre on +61 2 62613305 from overseas or within Australia on 1300 555 135. Follow FairfaxForeign on Twitter Marya Tabassum, 21, a British pilgrim who was injured along with her brother, Haroon, after a construction crane collapsed at the Grand Mosque earlier this month. Credit:AP Follow FairfaxForeign on Facebook