Millions of Muslims from around the world have started arriving in the Saudi Arabian city of Mecca ahead of the annual Hajj pilgrimage, a central pillar of the Islamic faith that re-enacts the actions of the Prophet Muhammad from more than 1,400 years ago.

Worshippers from more than 150 countries began gathering on Friday in the city, one of the holiest sites in Islam, to prepare for the five-day pilgrimage which starts on Saturday, September 10.

A spiritual journey meant to cleanse the faithful of sin and bring them closer to God, this year's Hajj is expected to be attended by more than 1.5 million pilgrims.

To address security concerns, nearly a thousand new surveillance cameras have been installed at Mecca's Grand Mosque, which will monitor crowd numbers, and the Jamarat stoning (a symbolic stoning of the devil based on historic tradition) will be more tightly controlled than in previous years.

Also for the first time, pilgrims will be given electronic bracelets storing personal and medical information that will help authorities provide care and identify people.

WATCH: Experience the journey of a Hajj pilgrim in 360-degree video

Water-resistant and connected to GPS, the devices will also instruct worshippers on timings of prayers and a multilingual help desk will guide pilgrims around the various rituals.

Last year's Hajj was marred by a stampede that killed more than 750 people. However, counts carried out by countries who repatriated bodies showed that more than 2,000 people may have died in the crush, according to news agencies.

The disaster deepened tensions between Riyadh and Tehran, as many of the pilgrims killed were Iranian.

Relations between the two countries hit a new low earlier this year when they failed to reach a deal on arrangements for Iranian citizens attending this year's pilgrimage.

Taking part in the pilgrimage at least once in one's lifetime is a major obligation for all able-bodied Muslims of financial means [Reuters]

Source: Al Jazeera News