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.

The kingdom has installed hundreds of coolers and cracked down on unregistered Muslim pilgrims, after 1,300 people died last year.

A Saudi government spokesperson says more than 1.5 million foreign pilgrims are in the country for this year's Hajj.