Some 288 "citizens and residents were arrested for violating hajj regulations," Lieutenant General Mohammed al-Basami, head of hajj security, told a press conference broadcast on state-run media, adding they were each fined 10,000 Saudi riyals (around $2,600).

Officials have also imposed a security cordon around Mecca, Islam's holiest city where the Grand Mosque is located, and barred nearly 100,000 people in more than 69,000 vehicles from entering, Basami said.

One million people, including 850,000 from abroad, are allowed to participate in this year's hajj -- a key pillar of Islam that all able-bodied Muslims with the means are required to perform at least once -- after two years of drastically curtailed numbers due to the coronavirus pandemic.

That is below the 2.5 million people who performed the hajj in 2019, before the pandemic hit, but significantly higher than the 60,000 people, all of them fully vaccinated Saudi citizens, who took part last year.

At least 650,000 pilgrims had arrived from overseas for the hajj as of Sunday, authorities said.

The pilgrimage officially starts Wednesday, but on Monday pilgrims were already performing rituals including circling the Kaaba, the large black cubic structure at the centre of the Grand Mosque.

The hajj, one of the five pillars of Islam, is a powerful source of prestige for the conservative desert kingdom, and Crown Prince Mohammed bin Salman.

But it poses a considerable security challenge and has seen numerous disasters over the years, including a 2015 stampede that killed up to 2,300 people and a 1979 attack by hundreds of gunmen that, according to the official toll, left 153 dead.