Intense heat has taken hold in many popular tourist destinations across the Mediterranean - including in Spain, Italy and Greece.

The extreme weather bringing temperatures of above 40C (104F) has put further strain on local medical and health services during the busy tourist period, with forecasters predicting even higher temperatures this week.

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Forecaster Simon Partridge said people heading to European hotspots should be prepared for the conditions.

"It's a massive shock to the system when you're there, so give yourself a chance to get used to the heat," he said.

Italian media said temperatures could reach 48C (118.4F) in Sardinia as sweltering conditions continue across southern Europe.

The Association of British Travel Agents said flights and holiday packages are continuing as normal - but Britons are being advised to stay hydrated, apply sun lotion and avoid the sun in the middle of the day.

The Foreign Office has recommended people check for the latest travel advice on its website.

Justine Rush, 53, who is in Corfu, told The Observer: "It's properly hot - too hot to go outside in the day, except when you're in the sea.

"We've had to stay in our room most of the day."

Paola Deitan, a 29-year-old from Wiltshire, was planning to travel with her best friend to Greece but has now opted for Barcelona, the newspaper reported.

She said: "I am worried about my health. I don't want anything to happen to me while on holiday."

Fifteen cities in Italy - most of them in the country's centre and south - were under heat advisories due to a high level of risk for older adults, children and other vulnerable people.

Last week, a 44-year-old man, who was painting a zebra crossing in 40C (104F) heat in the northern town of Lodi, lost consciousness and later died in hospital, local media reported.

More than 2,000 people have been evacuated as a wildfire raged on La Palma in the Canary Islands, while authorities in Greece opened air-conditioned areas in public buildings.

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Britons have been told they can change their holiday plans but normal conditions apply, including cancellation fees.

In the US, Death Valley along part of inland California's border with Nevada is approaching its highest-ever temperature.

The valley, which is acknowledged as the hottest place on Earth, could see temperatures above 53C (127.4F) this week.

About a third of Americans are under some type of heat advisory, watch or warning as the World Meteorological Organisation warned that with global warming and climate change, such temperatures are "becoming more and more likely".