Thousands of villages have been affected by the floods

Officials say more than 400,000 people have been marooned across the province after a week of heavy downpour.

Provincial authorities have described the situation as an "emergency" and troops have been called out to rescue people in danger of being swept away or marooned.

Thousands of homeless Pakistanis have sought shelter in temporary relief camps.

Officials admit they have not been able to feed all 40,000 men, women and children who have been registered at the camps.

The death of four people in the provincial capital, Karachi, has raised the death toll to 85, officials say.

'Frustrating'

Police say at least 21 people, many of them children, either drowned or were killed in flood-related accidents across Sindh over the past 24 hours.

Life has been badly disrupted in Pakistan's largest city, Karachi

"Even now, there are thousands of people we have been unable to reach," the police chief of Badin district, Javaid Akhtar Odoh, told the Reuters news agency.

Officials say some 5,000 villages in five districts have been badly hit, but the situation in Karachi, a city of 12 million, is particularly grim.

Met officials say the city recorded 79mm (3.1 inches) of rain on Monday which paralysed much of life in the country's commercial hub.

"It is certainly the worst since 1994," provincial spokesman Salahuddin Haider told the AFP news agency.

Banker Mohammed Saeed said: "It took me four hours to cover a distance of two kilometres. It was so frustrating that I parked my car on one side of the road and took a nap."