"We have a country which has endemic watery diarrhoea, endemic cholera, endemic upper respiratory infections and we have the conditions for much much expanded problems," Toole said.

The UN appealed last week for $459 million for immediate relief efforts. Officials said it has received 40 per cent - about $184 million - of that so far, and an additional $43 million has been pledged.

Makeshift camps

Many of the 20 million people affected by the floods are living in makeshift camps alongside their livestock.

"We have been told that for the past two weeks people here have not received any help," Al Jazeera’s Kamal Hyder, reporting from Dubair in northern Pakistan, said.

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"They are running out of food and they are running out of medicine."

The floods have killed about 1,600 people and inundated 1.7 million acres of wheat, sugar cane and rice fields, raising the prospect of food shortages in the coming months.

The World Bank on Monday announced that it will make $900 million in loans available for relief efforts.

A spokesman for the bank said funds will come through the reprogramming of planned projects and the reallocation of money.

Preliminary information indicates that "direct damage" from floods was greatest in the housing, roads, irrigation and agriculture sectors, the bank said.

Large parts of the flood-hit areas are still cut off by floodwaters.

'Marshall Plan' needed

Al Jazeera's Imran Khan, reporting from Shikarpur in the southern Sindh province, witnessed how hundreds of people, living in makeshift homes, were still waiting for food aid.

"There is no visible government presence in this part of the country, no international aid groups are operating here, yet.

"These people are going to be living in these conditions for months to come. The floodwaters [...] are not receding any time soon. And when they do, the true devastation of this disaster will be revealed," he said.

Pakistan won some aid pledges on Tuesday, however, amid concerns that money is not coming through fast enough. 

pakistan floods


  At least 1,500 people killed
  20 million people affected
  6 million people estimated to need food aid
  722, 000 homes damaged or destroyed
  700,000 hectares (1.7 million acres) inundated
  $459m needed to deal with immediate needs
  $184m received so far

State media in Saudi Arabia on Tuesday said the country had raised $20.5 million in aid on the first day of a national campaign for the Pakistani floods.

Japan also came forward to pledge an additional $10 million in emergency aid and Australia promised an extra $21.6 million.

"There are grave risks that the flooding will worsen Pakistan's social circumstances, but also its long-term economic circumstances will be potentially devastating," Stephen Smith, Australia's foreign minister, told ABC Radio.

The cost of rebuilding Pakistan could exceed $10 to $15 billion, the country's high commissioner to Britain said on Monday.

"It will take at least five years," High Commissioner Wajid Shamsul Hasan told the Reuters news agency.

He said the figures are a rough estimate because an assessment of the extent of the damage caused by the floods had yet to be carried out.

But the number gave an indication of the scale of the reconstruction needed.

"These floods have really dislocated everything," Hasan said.

"In the longer term, when the water subsides, we need reconstruction ... We'll have to have a long-term plan, something like the Marshall Plan."