Authorities in the eastern French town of Macon said a 53 year-old road-labourer died overnight of "malign hyperthermia" after working outside in temperatures of 33 degrees Centigrade (91.4 Fahrenheit).

Two elderly people died Tuesday in southwestern France as a result of the heat, and in the Netherlands two people died on the opening day of an annual walking event at Nijmegen.

In Spain a man who died of heat exhaustion in the northwest region of Galicia was the second to succumb after a man died in Murcia in the southeast on Sunday.

Forecasters in Britain said temperatures would peak Wednesday, reaching 39 degrees Centigrade in parts of the southeast. Belgium, Germany and Scandinavian countries were also experiencing unusually hot weather.

Local authorities in Britain poured gravel on roads to counter the effects of melting asphalt, and some schools and offices were closed. Lions at a zoo in Colchester were given ice cubes containing blood.

The heatwave recalled the summer of 2003, when some 30,000 mainly elderly people died across Europe as a result of dehydration and heat-stroke, but medical authorities in France and elsewhere said lessons had been learned and a repeat was unlikely.

French Prime Minister Dominique de Villepin was to visit an old people's home in Paris Wednesday to review procedures.

"There is no reason for disquiet, but we have to be vigilant and the health protection messages have to be constantly repeated," said Health Minister Xavier Bertrand.

In France the electricity supplier EDF was buying in energy from neighbouring countries because of the high use of air-conditioning, and falling output from hydro-electric and nuclear power stations as a result of low, warm rivers.

The soaring temperatures were likely to fall somewhat from Wednesday evening with the arrival of thunderstorms from the west, but it would remain hot, forecasters in France said.

The head of a French research laboratory said the unusually high temperatures were linked to global warming.

"The rules are changing, there's no doubt about it. This is the start of a process. We can expect heatwaves to be more frequent and more extreme as a result of the general rise in temperatures linked to greenhouse gas emissions," said Herve Le Treut , drector of the National Centre for Scientific Research.

Italy's main farmers' union said the country was suffering one of the worst droughts in 30 years with the situation in the north and the centre particularly bad.

Water levels in the lakes of northern Italy have fallen to historic low levels, making the irrigation of crops difficult, the Coldiretti union said in a statement.

A spokeswoman for Britain's Met office said: "We think there's a possiblity of the record being broken in the area to the west of London, where there is a concentration of hot air."

The highest temperature ever recorded in Britain was 38.5 C in Kent on August 10, 2003.

The London underground system, the oldest in the world, was a furnace on Tuesday with a record temperature of 47 C. Bus passengers fared even worse, with temperatures on buses in the City of London, the main financial district, reaching 52 C.

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