Hajj is the fifth pillar of Islam, a religious duty that must be carried out at least once in the lifetime by every able-bodied Muslim who can afford Hajj once in life time.

The world's largest annual pilgrimage, the Hajj, began on Sunday with a pilgrims total up to 2.5 million this year.

Authorities say permits have been granted to 1.7 million foreign pilgrims, with a further 200,000 or so issued to pilgrims from within Saudi Arabia and from neighbouring Gulf states.

The passage to Mina marks the official launch of the Hajj on the eighth day of the Muslim calendar month of Zulhajj.

The day is known as Tarwiyah as pilgrims in the past stopped at Mina to water their animals and stock up for the following day's trip to Mount Arafat.

At Mount Arafat, around 10 kilometres southeast of Mina, the pilgrims spend the day in prayer and reflection.

After sunset, they move on to Muzdalifah, halfway between Mount Arafat and Mina, where they spend the night.

On Tuesday, the first day of Eid-ul-Azha, the pilgrims' head back to Mina after the Fajr prayers.

They will then perform the first stage of the symbolic `stoning of the devil and make the ritual sacrifice of an animal, usually a lamb.

No major incidents have been reported this year since the pilgrims began gathering in Makkah.

The city's Grand Mosque has been flooded with the faithful, with an estimated 1.7 million taking part in the main weekly Muslim prayers on Friday.