More than 200 people have died in a heatwave in southern Pakistan, officials said Monday, as the government called in the army to help tackle widespread heatstroke in the worst-hit city Karachi.

The death toll in Karachi, the country's largest city, where temperatures hit 45 degrees Celsius (111 Fahrenheit) at the weekend, is at least 202 and a further 11 deaths were reported in southern parts of central Punjab province.

"The death toll from the heatwave has crossed the figure of 200 in Karachi as we have confirmed causalities of 140 in Jinnah Postgraduate Medical Centre (JPMC)and 62 from Civil Hospital Karachi," the provincial health minister Jam Mehtab Dehar told AFP.

He said the true figure could be much higher, as the toll excluded other hospitals and deaths yet to be recorded elsewhere.

Doctors say most of those who have died succumbed to heatstroke.

The Islamic fasting month of Ramadan, during which devout Muslims abstain from all food and drink during daylight hours, began on Friday, coinciding with what is usually the hottest time of year in Pakistan.

An AFP tally based on information from five hospitals around Karachi suggested the toll there could be as high as 249.

National Disaster Management (NDMA) spokesman Ahmed Kamal told AFP the government had asked the army and paramilitary Rangers to help relief efforts which will include setting up heatstroke treatment centres around the city.

Coping with the scorching heat has been made harder by the power cuts that are a daily feature of life in Pakistan.

The government of Sindh, the province where Karachi is located, has imposed a state of emergency at all hospitals, cancelling leave for doctors and other medical staff and increasing stocks of medical supplies.

Sher Shah, a veteran medical practitioner and former president of the Pakistan Medical Association said Karachi's poor were most at risk.

In Karachi, a city of 20 million people, electricity shortages crippled the water supply system, hampering the pumping of millions of gallons of water to consumers, the state-run water utility said.

Pakistan's Met Office said temperatures hit 43 C in Karachi on Sunday and 49 C in the southwestern city of Turbat, close to the Iranian border.

More hot and humid weather is predicted for the coming 24 hours, though thunderstorms forecast for later in the week could bring cooler weather.

The deaths come a month after neighbouring India suffered the second deadliest heatwave in its history, with more than 2,000 killed.

Hundreds of mainly poor people die at the height of summer every year in India, but this year's toll was the second highest in the country's history.

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