More than 100 people have died from heatstroke in the southern Pakistan port city of Karachi in the last two days, officials have said.

Seemi Jamali, a spokeswoman for the city's Jinnah Hospital, confirmed the deaths today. She said hundreds more have been admitted to the hospital with heat-related ailments, including fever and dehydration.

Karachi is in the grip of a rare heatwave, with temperatures soaring to 45C (113F). A collapse of the local power grid over the weekend made matters worse.

Meteorologist Mohammad Hanif said the heatwave is the worst in at least a decade, but that the arrival of monsoon rains in the coming days should bring relief.