The world's largest cooling system is in operation at the Grand Mosque in Makkah, as more than a million Hajj pilgrims gather in the Saudi city amid the summer heat. The annual pilgrimage is to begin on Wednesday and Saudi authorities have vowed that the event will be safe as temperatures soar.

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

Saudi officials say they have stopped more than 269,000 Muslims without permits for the Hajj pilgrimage from entering Mecca.