Hundreds of thousands of Muslims have flocked to the Saudi holy city of Mecca for the Hajj pilgrimage unfolding this year in the shadow of the Gaza war.

One of the world's largest annual religious gatherings officially begins on Friday, and Saudi officials are trying to keep the focus on prayers.

The Gulf kingdom's minister in charge of religious pilgrimages, Tawfiq al-Rabiah, warned last week that "no political activity" will be tolerated.