Record heatwaves sweep through US and Europe

Record heat is forecast around the world from the United States, where tens of millions are battling dangerously high temperatures, to Europe and Japan, in the latest example of the threat from global warming.

Italy faces weekend predictions of historic highs with the health ministry issuing a red alert for 16 cities including Rome, Bologna and Florence.

The meteo centre warned Italians to prepare for "the most intense heatwave of the summer and also one of the most intense of all time".

The thermometer could hit 40 degrees Celsius in Rome by Monday and even 43°C on Tuesday, smashing the record 40.5°C set in August 2007.

The islands of Sicily and Sardinia could wilt under temperatures as high as 48°C, the European Space Agency warned - "potentially the hottest temperatures ever recorded in Europe".

Greece is also roasting.

"Parts of the country could see highs as much as 44°C on Saturday," according to the national weather service EMY. The central city of Thebes sweated under 44.2°C on Friday.

The Acropolis, Athens's top tourist attraction, will on Sunday close during the hottest hours for the third day running.

Access to the UNESCO-listed archaeological site dating to antiquity is being suspended from midday to early evening "to protect workers and visitors", the culture ministry said.