The US envoy to Pakistan has warned that the world will only be able to fund around 25% of the "tens of billions" of dollars needed to rebuild Pakistan after the floods, meaning its government will have to make up the shortfall.
Richard Holbrooke said that America would not condition its assistance to the country, but warned the US Congress might not be generous if it felt that Pakistan was not taxing its own citizens enough.
Pakistan has one of the lowest tax-collection rates in the world, something that critics have pointed out in recent weeks as its leaders seeks international aid.
The country's economy survives on international assistance, and the floods are expected to badly slow economic growth further.
Monsoon rains triggered massive floods six weeks ago that have made some eight million people homeless.