Karachi: More than 450 people have died from a three-day heatwave in southernPakistan, officials said Tuesday, as medics battled to treat victims after a state of emergency was declared in hospitals.

The death toll in worst-hit Karachi, where temperatures hit 45 degrees Celsius (111 Fahrenheit) at the weekend was at least 450 while another eight to 10 people died in other parts of southern Sindh province, said Sabir Memon, a senior provincial health official.

"More than 450 people have died due to heat stroke in the past three days," Memon told AFP.

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

Semi Jamali, a doctor at Karachi's largest hospital said they had treated about 3000 patients suffering from heat stroke.

"More than 200 of them were either received dead or died in hospital," Jamali told AFP.

Another 67 people died in another hospital, the Civil Hospital, an official there said.

Pakistan's largest charity, Edhi Welfare Organisation, said their two morgues in the city had received more than 400 corpses.

"More than 400 dead bodies have so far been received in our two mortuaries in past three days," Edhi spokesman Anwar Kazmi told AFP.

"The mortuaries have reached capacity." 

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 Celsius in Karachi on Sunday and 49 Celsius in the southwestern city of Turbat, close to the Iranian border.

India's brutal heatwave last month led to at least 2,005 deaths, most in the southern states of Andhra Pradesh and Telangana.

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.