The flow of international aid to flood-hit Pakistan is almost at a standstill, says the United Nations.
It says relief efforts are being stretched by the unprecedented scale of the disaster.
Thousands of people remain trapped by floodwaters in the hardest-hit southern province of Sindh.
The deluge has engulfed an area the size of England, affecting more than 18 million people, including eight million who are dependent on aid handouts to survive.
Pakistan's ambassador to the UN, Abdullah Hussain Haroon, has called for an investigation into claims that wealthy landowners diverted flood waters towards villages to protect their crops.
The International Monetary Fund is to give Pakistan $630 million in emergency aid, providing some relief for a government overwhelmed by the disaster and facing renewed militant violence.
IMF managing director Dominique Strauss-Kahn says the funds will be dispersed in coming weeks.
He says discussions with a delegation led by Pakistan's finance minister on how to reorganise a $15 billion IMF loan program will continue.
Meanwhile, a three-day period of mourning has begun in Pakistan after bomb attacks on a Shia Muslim procession in the city of Lahore killed 31 people and wounded 170.
Lahore has been the scene of sectarian violence between Sunnis and Shias, but there had been a lull in the past months as floods devastated the country.