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.

Saudi Arabia has implemented strict security measures for Hajj, including deploying the US-made Patriot missile defence system around Mecca.

Millions have made the annual pilgrimage to Mecca. The kingdom faces scrutiny over safety after more than 1,300 people died last year.