Pakistan is calling for UN aid after monsoon rains caused flooding in the province of Sindh, killing at least 200 people and prompting fears of another major disaster.

Almost five million people have been affected as torrential rain submerged more than 20,000 villages.

One can hardly find a dry place in the flood-hit areas

President Asif Ali Zardari asked for the help of the UN and other international organisations over the weekend as further heavy rains were forecast for the coming days. Sindh was among the worst hit region in last year’s floods in Pakistan, which killed about 2,000 people and made 11 million homeless.

The UN, which has described the situation as critical, is carrying out an urgent assessment. Aid organisations warned in July that Pakistan was unprepared for a repeat of flooding with hundreds of thousands still in camps a year after the country’s worst-ever natural disaster.

Witnesses said that the situation appeared to be worse than last year. Amar Guriro, an environmentalist and journalist, said: “One can hardly find a dry place in the flood-hit areas. I found hundreds of the corpses of dead people, goats, buffaloes, cows, donkeys and other animals.”

More than 2,500 relief camps have already been established in the province giving shelter to more than 225,000 people, officials claim. They admit, however, that since all the main roads leading to the affected area are under water it is difficult for supplies to get through. Mr Guiriro said he saw no evidence that food, shelter and medical supplies were reaching those worst affected.

In a statement the UN Office for the Co-ordination of Humanitarian Affairs said: “The situation for those impacted by recent monsoons and subsequent floods is critical, with thousands of people in need of life-saving assistance due to the lack of food and safe drinking water and the loss of livelihoods and homes.”

The UN children’s agency said up to 2.5 million children in southern Pakistan had been affected by the monsoon floods