The United Nations revised up its humanitarian appeal for Pakistan five-fold, to $816 million from $160 million, as a surge of water-borne diseases and fear of growing hunger posed new dangers after weeks of unprecedented flooding.

"We have no space to give our economy any stimulus ... the developed world should accelerate funding for climate hit disasters," the climate change minister, Sherry Rehman, told an conference on aid for Pakistan in Geneva.

The floods have submerged huge swathes of the South Asian country and killed nearly 1,700 people. Hundreds of thousands of displaced people are living in the open.

The deluge, brought by record monsoon rains and heavy glacial melt in northern mountains, has impacted 33 million people out of a population of 220 million caused damage the government estimates at $30 billion.

The government and the United Nations have blamed climate change for the disaster.

Julien Harneis, the U.N. resident coordinator and humanitarian coordinator in Pakistan, said the $816 million target for the appeal was "absolutely not enough".

Rehman said Pakistan was in urgent need of medicines for 8.2 million people and would need to import extra supplies of food.

Tedros Adhanom Ghebreyesus, director general of the World Health Organization, told the meeting Pakistan was "on the verge of a public health disaster".

(Reporting by Asif Shahzad, Writing by Tanvi Mehta; Editing by Robert Birsel)

By Asif Shahzad