Two elderly people died as a withering heatwave blasted Cyprus for a fourth day Wednesday and electricity workers went on strike cutting air conditioning, doctors and officials said.

The overall toll from the baking temperatures climbed to three with the deaths or a man and a woman in their mid-90s, as the thermometer soared to 42 degrees Celsius (108 Fahrenheit).

The electricity workers' strike put air conditioning systems at hotels and office blocks out of action and left villages without power through the killer hot spell.

Unions launched the action because they are opposed to a government move to build a private storage unit for liquefied natural gas that they say would unnecessary cause job losses on the holiday island.

The sizzling temperatures seven degrees above normal have triggered record demand for electricity as people try to stay cool.

Electricity authority spokesman Costas Gavrielides said villages had been affected for only about 30 minutes by strike action.

"There were only mild interruptions as the strike measures were relaxed," he said.

A punishing dry spell is also putting severe pressure on the Mediterranean island's water reserves with dams only at around 23 percent capacity.

The meteorological service said the freak heatwave will continue until Saturday when maximum temperatures are expected to dip to around 35 degrees Celsius, the average for June.

Cypriots are being advised to stay in the shade, drink plenty of fluids, wear light clothing and not take strenuous exercise.

The health ministry has warned employees to prevent staff working outdoors during the mid-afternoon bake.

Casualty departments have been put on alert to cope with a possible influx of heat-related cases.

The government is better attuned to tackling heatwaves after being heavily criticised for badly handling a heatwave in 1998 when more than 60 people died.