It's unbelievably hot there, temperatures of over 50 degrees right now, and it's feared the death toll could go much, much higher.

Unregistered pilgrims do not have access to proper facilities, things like air conditioning and official transport.

As Caroline Hawley now reports...

It's a sacred duty for Muslims to perform the pilgrimage once in their lifetime, if physically and financially able, and it's a colossal logistics operation for the Saudi authorities.

They've been criticised in the past for the way they've handled the Hajj, for deadly stampedes, but this year the danger came from blistering heat.

There was water on hand, large sprinklers, and some air-conditioned areas for the more than 1.8 million pilgrims.

But it was more than 50 degrees in the shade, and the scorching temperature took a terrible toll.

Ather Hussain is imam of Leicester's central mosque.

He's just returned home from Saudi Arabia, scarred by what he saw.

It was undoubtedly a traumatic experience.

You would walk and you simply wouldn't know where to look, because everywhere you turned you would see someone struggling in some way or the other, people completely drowned in sweat.

It's not just the frail and the elderly who were affected.

I saw perfectly fit individuals who were struggling just to make 50 yards.

In the village of Menufia in northern Egypt, a family mourns. 70-year-old Effendia sold jewellery to pay for the pilgrimage.

She had a tourist visa, and like many others, wasn't officially registered for the Hajj.

Her children say she was left to walk for miles, taken advantage of by an unscrupulous tour operator.

She called home as she was dying.

I screamed and couldn't believe it.

She phoned my brother and told him she felt her soul is leaving her body.

I wish I was with her.

The casualties come from many countries, and there are fears that climate change will in The charity Islamic Relief has called for urgent steps to inform pilgrims of the risks and to ensure that their safety is paramount.

Caroline Hawley, BBC News.