And both Switzerland and France had switched off nuclear reactors as the water used for cooling was in danger of overheating nearby rivers.

The German Weather Service (DWD) issued a red alert for most of the country on Saturday, and said late afternoon that it had recorded its highest ever temperature with 41.5C recorded in eastern Germany.

"It can't be ruled out that temperatures could approach 42C," the service said, which would mean another all-time heat record just a day after the previous one.

Denmark's weather service said early afternoon Saturday that the country had recorded its highest temperature ever, and then an hour later said the record had lasted just an hour, with the mercury hitting 37C just north of Aarhus.

The Czech Republic also recorded its highest-ever temperature, with a reading of 40.6C just north of Prague.

Scientists have shown that recurring heatwaves are a clear marker of global warming driven by humans burning fossil fuels - and are set to become more frequent, longer and more intense.

Experts said a "heat dome" of trapped air from north Africa was causing the intense weather, and although the phenomenon was not unprecedented, the temperatures were.

'Everything is hot'

Romania was the latest country to issue a red alert, putting out a warning that almost the entire country would face extreme heat from Monday to Wednesday.

Slovakia had issued a similar warning and confirmed that Friday night had been the warmest on record with temperatures not dropping below 26.3C.

Denis Ovdyienko, a courier, told AFP in Bratislava on Friday he was struggling to keep cool and had to rely on public fountains.

"I feel like everything is warm. The road is warm, my phone is warm, my head is warm, everything is hot," said the 26-year-old.

"After four o'clock, the fatigue starts to kick in."

The Czech Republic, Hungary and Moldova were also on the highest alert for the weekend, with Balkan countries also bracing for a tough few days.

'Exceptional, extreme'

At least 193 million people in Europe were expected to experience temperatures above 35C on Saturday, according to AFP calculations based on forecasts, with Germany the hardest hit.

Although a slew of events were cancelled, many in Germany were soldiering on.

The Berlin Philharmonic said it would continue with its traditional end-of-season outdoor concert in Berlin despite temperatures of up to 41C, but the dress code would be relaxed.

"The gentlemen will perform without jackets, but with a black shirt on top," a spokeswoman for the orchestra said.

They would be allowed to roll up their sleeves, and the ladies' tops only need to cover the elbow and do not necessarily have to be long-sleeved.

The authorities in Paris, however, forced the abandonment of several events, including the city's annual Pride March.

Deputy mayor in charge of health, Antoine Alibert, said hospitals in the French capital were saturated - echoing comments by several other city leaders.

He told local media stretchers were "piling up in the corridors", emergency calls had skyrocketed and hospital visits were on the rise.

"We are in the midst of a health crisis. This is an exceptional and extreme heatwave event," he said.

But in Budapest, the city's Pride march went ahead despite 40C weather.

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