The death toll from a major heatwave sweeping across India has reached at least 800 people, as roads in New Delhi melt in temperatures nearing 50 degrees Celsius.

Hospitals were on alert to treat victims of heatstroke and authorities advised people to stay indoors with no end in sight to the searing conditions.

In the worst-hit state of Andhra Pradesh, 551 people have died in the past week as temperatures hit 47C on Monday.

• India heatwave kills more than 430

“The state government has taken up education programs through television and other media to tell people not to venture into the outside without a cap, to drink water and other measures,” said P Tulsi Rani, special commissioner for disaster management in the state.

“We have also requested NGOs and government organisations to open up drinking water camps so that water will be readily available for all the people in the towns.”

Large parts of India, including the capital New Delhi, have endured days of sweltering heat, prompting fears of power cuts as energy-guzzling air conditioners work overtime.

The Hindustan Times daily said the maximum temperature in the capital hit a two-year high of 45.5C on Monday – five degrees higher than the seasonal average.

The paper carried a front-page photo of a main road in the city melting in the heat, its zebra pedestrian crossing stripes curling and spreading into the asphalt.

“It’s baking hot out here – our outing has turned into a nightmare,” said Meena Sheshadri, a 37-year-old tourist from the western city of Pune who was visiting Delhi’s India Gate monument with her children.

“My throat is parched even though I’ve been constantly sipping water.”

In Telangana state, which borders Andhra Pradesh in the south, 231 people have died in the past week as temperatures reached 48C over the weekend.

In the western state of Orissa 11 people were confirmed to have died from the heat.

Monsoon rains weeks away

India’s Meteorological Department issued a “red box” warning for the state Tuesday and Wednesday, meaning the maximum temperatures would remain above 45C.

Another 13 people have died in the eastern state of West Bengal, where unions urged drivers in the city of Kolkata to stay off the roads during the day.

Hundreds of people – mainly from the poorest sections of society – die at the height of summer every year across India, while tens of thousands suffer power cuts from an overburdened electricity grid.

India’s power industry has long struggled to meet rapidly rising demand in Asia’s third largest economy, with poorly maintained transmission lines and overloaded grids.

With no end in sight to the hot, dry conditions, the Hindustan Times warned that some of the worst-affected states could be plunged into drought before the monsoon rains arrive.

The monsoon is forecast to hit the southern state of Kerala towards the end of this month before sweeping across the country, but it will be weeks before the rains reach the arid northern plains.