More than two million Muslims from around the world began the hajj pilgrimage at Islam's holiest sites yesterday, a religious duty and an epic multi-stage journey.

This year sees pilgrims from Shia Iran return to Makkah in Saudi Arabia after a hiatus following a diplomatic spat between the regional rivals and a deadly stampede in 2015.

It also comes with the Gulf mired in a major political crisis that has seen thousands of faithful who would usually make the journey from neighbouring Qatar stay away.

On the esplanade of Makkah's Grand Mosque, the excitement was palpable as crowds from all four corners of the world gathered for a pilgrimage that all able Muslims are required to perform at least once in their lives.

Tidjani Traore, a public service consultant from Benin, said he was on his 22nd pilgrimage at the age of 53.

"Every time, there are new emotions," he said. "There are new innovations for organising and hosting the pilgrims. Now, for example, the tents are air-conditioned."

Wearing the simple garb of the pilgrim, the faithful waited at dawn with their suitcases for buses to take them to Mina five kilometres (three miles) to the east.

There, hundreds of thousands will gather today before setting off at dawn to climb Mount Arafat, the pinnacle of the hajj.

First, however, they must perform a ritual walk known as the tawaf seven times around the Kaaba, a black masonry cube wrapped in a heavy silk cloth embroidered in gold with Koranic verses at the centre of Makkah's Grand Mosque.

The shrine is the point towards which Muslims around the world pray.

"I still have to finish the tawaf!" said a breathless Nour, 30, from Saudi Arabia as she rushed past without stopping.