Millions of Muslims have gathered in Saudi Arabia to perform the hajj, the Islamic pilgrimage to the holy cities of Mecca and Medina that begins today.
The annual ritual is one of the Five Pillars of Islam.
But overall numbers are down this year due to concerns about swine flu, with attendance of around 2.5 million falling considerably short of last year's 3 million mark.
Despite alarms raised after Saudi officials reported over the weekend that four pilgrims had died of swine flu, health authorities say that they are not seeing any evidence of an increase in the spread of the H1N1 strain.
Saudi Health Minister Abdullal Abdul-Aziz al-Rabeea says he's confident his country is prepared.
"I'm very confident -- confident first of all, in the preparations. Confident in the team of the Ministry of Health, confident in our supplies, and confident in the facilities that are enough, if needed," Rabeea said. "So far the indicators are showing very good results, limited numbers, and we, so far, from day to day, we are not seeing anything alarming."
Saudi authorities have taken extra measures to provide medical facilities and personnel, and have installed equipment to screen pilgrims for signs of the virus.
More than 100,000 police and security force members are on duty in the holy cities of Mecca and Medina.
First undertaken by Prophet Muhammad 14 centuries ago, the hajj is one of the world's biggest mass displays religious devotion. It is an obligation for all able-bodied Muslims who are financially capable of undertaking the journey.
Hamido Abdul Rahim, a Canadian-Moroccan who is in Mecca to perform the hajj, says he's not afraid of the pandemic flu.
"There is no swine flu here in Saudi Arabia, thank God," Rahim says. "Also, thank God, everything is available here in this country, medicines, doctors, everything."
Muslims believe the hajj originates from the time of Prophet Ibrahim (Abraham) thousands of years ago.
The five-day pilgrimage consists of a number of rituals. Millions of hujjaj, or pilgrims, perform "tawaf" when they walk counterclockwise seven times around the Kaaba, the cube-shaped shrine located near the center of Great Mosque in Mecca.
Muslims consider the Kaaba the most sacred spot on Earth and face it during their five daily prayers.
Muslim pilgrims in Mina, Saudi Arabia before the start of the 2009 hajj.
While performing the hajj, the pilgrims also kiss the Hajra Aswad, the Black Stone in the corner of the Kaaba. They run seven times between Mount Safa and Mount Marwah and drink from the Zamzam Well.
During the second stage of hajj, the pilgrims visit the holy places of Mount Arafat, Muzdalifah, and Mina outside Mecca. There they engage in the ritual stoning of the devil by throwing stones at the three pillars in Mina. The also sacrifice animals to commemorate Ibrahim's sacrifice, and then shave their heads.
After celebrating the three-day global festival of Eid al-Adha, the pilgrims visit the holy city of Medina, where the Prophet Muhammad is buried and where he lived part of his life in exile.compiled from agency and RFE/RL reports