At least 13 Iranian nationals passed away while performing the Hajj pilgrimage in Saudi Arabia amid rising temperatures there, according to Iran's state media reports.

Tens of thousands of pilgrims in Saudi Arabia utilized the Metro service to travel between the holy sites during this year's annual Hajj season, the Saudi Transport Ministry said.

Saudi Arabia has barred more than 269,000 people without permits for the annual Hajj pilgrimage from entering Mecca this week, authorities said, as the world's largest annual gathering of people has officially begun.