Four people have died in a packed train without air conditioning as temperatures soared to nearly 50C in India.

The victims, aged between 69 and 81, were Hindu pilgrims returning to the southern state of Kerala after visiting the holy city of Varanasi in the country’s north.

Dozens of people are reported to have died in the past month as a suffocating heatwave grips much of India.

The latest deaths came on Tuesday as temperatures hit 48C.

Railway official Manoj Kumar said the four pilgrims were travelling in the same group and collapsed in their carriage. Doctors were called to Jhansi station but pronounced them dead. The victims’ bodies have been sent for autopsies.

A fifth passenger was reportedly taken to hospital in a critical condition.

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Many poorer Indians are priced out of air-conditioned carriages, which are more expensive to travel in despite the deadly heat.

The recent heatwave has forced schools and universities to close, with people advised to stay indoors during daytime.

Authorities have been hosing down the baking streets with water in the hottest states, where temperatures soared near-record levels of 50.6C earlier this month.

Police have been tasked with guarding water tankers in Madhya Pradesh state following deadly fights over supply.

Hospitals have fitted emergency wards with extra air conditioners, coolers and medicines, as water shortages and sunstroke claim casualties.

The heatwave is part of a trend of rising temperatures in India. Last year was the sixth warmest since national record-keeping began in 1901, and 11 of the 15 warmest years on record have occurred since 2004.