Armed with an ice-cold water bottle and a wet cloth, the 35-year-old Egyptian was doing his best to stay cool while wearing his mandatory mask and hair cap.

"It's hot outside, but inside, it's like fire," he said, shoving a board loaded with flatbreads into a large wood-fired oven.

"Standing here in front of the fire is like hell," he added as customers waited in the shade outside the small Riyadh bakery.

In arid Saudi Arabia, summer temperatures regularly reach 50C, leaving streets empty for much of the day.

To protect labourers, the kingdom bans work under direct sunlight and outside during the hours of most intense heat from mid-June until mid-September.

But these rules do little for indoor workers, many of whom, like Ahmed, have no choice but to toil near manmade sources of heat even at midday -- the hottest time of the day, which also coincides with busy lunch breaks.

"Here by the fire, I suffer on both sides," he said, caught between the oven and the bakery's door, which does not shut properly and allows in hot air from outside.

In June, Human Rights Watch called on Gulf countries to extend protections for workers toiling in the heat, considering current measures "insufficient".

A spokesperson for the human resources and social development ministry told AFP the kingdom had "clear occupational safety and health regulations to protect workers from heat stress across all sectors".

The ministry "conducts targeted inspection campaigns, acts on public reports through its hotline and mobile app, and enforces penalties for non-compliance", they added.

Ahmed left Egypt five years ago after he was offered 3,000 riyals ($800) to work in Riyadh -- a sum the struggling baker could not refuse.

"I keep working and I endure for the sake of my family", who now have a better life thanks to his higher pay, he said.

He works from 11:00 am to midnight, but fatigue sets in early.

"By midday, I'm completely exhausted," he said.

He cannot walk after his shift and has to "lie down for at least 30 minutes to get back to normal".

- Heat exhaustion -

Across the city, workers in bakeries, restaurants and laundries labour near indoor sources of heat all day long.

Karim Elgendy, who heads the Carboun Institute think tank, warned they were just as exposed to health risks as those working outdoors.

"Exposure to direct sunlight at 40C temperatures for an hour is comparable to being in front of an oven at 200C for a similar period," Elgendy said, warning that heat exhaustion and excessive sweating "can lead to severe dehydration, which puts pressure on vital organs".

People working by an oven should take frequent breaks away from the heat, he added.

But Hani al-Duaisi, who manages a grilled chicken shop, said that was impossible as the restaurant was packed with customers for most of the day.

Along with three employees, the 26-year-old Yemeni toils in a cramped kitchen packed with a grill, a charcoal stove and large pots filled with steaming rice.

"Even if you turn 10 air conditioners on, it won't cool the kitchen," he said, wiping away some sweat.

Nearby, some customers began complaining about slightly delayed orders.

"I feel like people outside live in one world, and we live in another," said Duaisi.

"Our world here is hell."