France’s health minister said “young people are also suffering from cardiac arrests”. The ambulance service in Paris had seen four times more cardiac arrests than normal over a 24-hour period, said Rist, while stressing there were no confirmed figures for the number of deaths linked to the heatwave.

Paris mayor Emmanuel Grégoire said the mortality rate was on the rise in the capital.

“We must not believe we are invulnerable,” he told French TV. “I am thinking especially about the youth… At about 19:30 last night… I saw 100 or so joggers on the street. Frankly, that’s irresponsible.”

“It’s fine to take a couple of days off from exercising,” he added.

Stéphanie Rist said everyone had to adjust their personal activity to the high temperatures: “Even if you are young and in good health with no underlying medical issues, this heat will affect you too.”

Even cycling came with risks, she warned, from high temperatures that lasted a week, as people would start feeling faint and might fall and even end up in hospital.

In a bid to ease pressure on the capital’s hospitals, Parisians will also be restricted from drinking alcohol in public from noon on Friday until 07:00 on Saturday. Licensed bars and restaurants are exempt.

Bans on takeaway alcohol sales will also be in effect from 18:00 on Friday until 07:00 on Saturday.

Both restrictions will be in place during the same hours from Saturday to Sunday.

Speaking to local media, Paris police chief Patrice Faure said: “We are reaching a saturation point in hospital facilities.”