Pakistan has suffered devastating floods in the past two years, including the worst in its history in 2010 when catastrophic inundations across the country killed almost 1,800 people and affected 21 million.

This year monsoon floods in Pakistan have killed 480 people and affected more than five million, according to the government's disaster relief agency.

"There is a funding shortage -- as is most often the case in protracted crisis -- $79 million dollars are urgently required to meet immediate needs," Assistant Secretary General for Humanitarian Affairs Catherine Bragg said.

"Winter is coming, making the need even more urgent," she told reporters after a visit to affected areas.

"Hundreds of thousands are still in need of food and shelter - and over one million people are estimated to still be in need (of) health care, water and sanitation services and agricultural inputs," Bragg said.

The UN has estimated a total of $169 million dollars is required including the $79 million for emergency relief, she said. So far it has has received only $52 million in pledges.

"We look to donors for their generosity."

As in the previous two years, most of those hit by the latest floods were in southern Sindh, where the National Disaster Management Authority (NDMA) said more than three million have been affected, with 887,345 in Punjab and nearly a million in Balochistan.

More than 159,023 people around the country have sought shelter in 108 relief camps since early September, though this figure is down from the 290,000 reported by NDMA earlier.

The data published by NDMA last week said more than 1.1 million acres (450,000 hectares) of crops were affected by the floods.

In addition to those who have fled natural disasters, nearly half a million Pakistanis are estimated to have escaped fighting between soldiers and militia on the Afghan border this year and taken shelter at Jalozai camp, near Peshawar.