Flood waters across Pakistan's Sindh province have destroyed or damaged hundreds of thousands of homes and flooded 4.2 million acres since late August, according to the UN, with the rains showing little sign of abating.

"The situation in Sindh is already serious and there will be more flooding and more problems because of these rains," meteorology department official Arif Mehmood told Reuters. ©UNICEF Pakistan/2011/Warrick Page

Karachi and its surroundings has been especially badly hit by the torrential rains with thousands displaced, schools shut down, markets forced to close and commuters abandoning their vehicles as rain water flooded the streets.

The floods are bad news for Pakistan's cash-strapped government, still struggling to help victims of last year's devastating floods. It faces another major test as monsoon rains sweep across the south.

For many people the rain bore frightening similarities to 2010, when millions were displaced and about 1,600 people died in torrential monsoon rains. Sindh was one of the worst affected regions and some officials have said this year's floods could prove to be just as serious.

On Monday the UN said it had begun efforts to feed 500,000 people affected by the floods and rain, initially concentrating its efforts in the badly-hit Badin district of Sindh province.

Pakistan's disaster management chief has warned that the situation is worsening each day as water levels are rising because of more rain and poor drainage.

The UN children fund, Unicef, says that it is especially worried about the plight of children who are at risk of malnourishment and disease as the waters continue to rise. © UNICEF Pakistan/2011/Warrick Page