This week's hajj marks Iran's return after their absence last year following a massive stampede in 2015 that killed around 2,300 people, including 464 Iranians.

The tragedy sparked bitter recrimination from Tehran over the kingdom's custodianship of the sites in Mecca and Medina, western Saudi Arabia.

For the first time in nearly three decades, Iranian pilgrims were barred from the hajj last year, after several rounds of negotiations between the two Gulf heavyweights failed to overcome political and procedural differences.

Adding a further obstacle, the Sunni kingdom cut all ties with Shia Iran in January 2016 after its diplomatic missions in Tehran and Mashhad were torched by protesters angered by Saudi Arabia's execution of a prominent Shia figure.

But under a deal struck in March, about 86,000 Iranians have now arrived in Saudi Arabia for the hajj, joining two million Muslims from across the globe in converging on Mecca.

"I'm happy to see so many Iranians here... Political issues shouldn't interfere in a religious duty, especially the hajj," Abbas Ali, a 54-year-old Iranian, said Monday at Jeddah airport that is the main entry point for pilgrims.

"It's very difficult to describe my feelings. We shouldn't stop coming here because all of us are Muslims," the newly-arrived "haji" from Zahedan in eastern Iran told AFP.

The breakthrough came after several months of negotiations during which the two countries traded accusations of obstructing an agreement.

- Diplomats to inspect empty embassies -