KARACHI - Pakistani Prime Minister Nawaz Sharif has called for emergency measures as the death toll in a deadly heatwave in southern Pakistan reached nearly 700.

He has ordered the National Disaster Management Authority to take immediate steps to contain the crisis, reported the BBC. The army has also been called in to assist with relief measures.

Most of the deaths were in the port city of Karachi in Sindh province, where temperatures hit 45 deg C at the weekend. Elderly people were the worst affected.

While 612 people died in government-run hospitals, another 80 people died in private hospitals, said Sindh province's Health Secretary Saeed Mangnejo.

The death toll could mount as thousands of people are being treated for heatwave-related symptoms, some of whom are in critical condition.

"We are still receiving a neverending flow of patients," said Dr Seemin Jamali, joint director at Jinnah Postgraduate Medical Centre. "Some were brought in dead, while others died during treatment."

The soaring heat led to a surge in power demand, causing blackouts in many areas and sparking protests. Electricity shortages crippled the water supply system.

"We are diverting power from industry to residences," said Ministry of Water and Power additional secretary Hassan Nasir Jamy.

One lawmaker suggested that Parliament should turn off its air-conditioning for an hour to show solidarity with the people.

The deaths came as the majority Muslim country of about 200 million people observed the Islamic holy month of Ramadan, during which eating and drinking is forbidden from sunrise to sunset.

Some relief was on the cards, with pre-monsoon rains poised to hit Karachi yesterday evening, according to the Pakistan Meteorological Department.

BLOOMBERG, REUTERS, AGENCE FRANCE-PRESSE