Heavy monsoon rains caused flash floods along the Indus and Kabul rivers that have swept away homes, roads, crops and bridges.
Prime Minister Shehbaz Sharif called the flooding “the worst in the history of Pakistan” and estimated it could cost at least $10 billion to recover from the damage.
UN Secretary General Antonio Guterres echoed his assessment and described the floods as a "colossal crisis" before a planned visit to the country in September.
Indus River bursts its banks in Rajanpur
Images released by space technology company Maxar Technologies show the levels of destruction along the banks of the Indus River, which runs almost the length of the country.
Flash floods along the banks of the river caused by monsoon rains have devastated areas of the southern province of Sindh and the eastern province of Punjab.
Villages and farmland in Rajanpur and Gudpur, both in Punjab, have been almost entirely submerged by the river.
Farmland destroyed in Punjab province
An estimated 33 million people have been affected by the floods.
This amounts to around one in seven people in a country of 210 million.
The flooding has destroyed more than a million homes and left millions displaced.
Many of those displaced have been forced to find their own shelter, while about 500,000 people are living in organised camps.
Villages cut off in Gudpur and Rajanpur
The UN launched a formal $160 million appeal on Tuesday as Pakistan reels from the floods.
Several foreign countries have already began providing aid.
The UAE has begun operating an air bridge to transport humanitarian aid including supplies, shelter material, food and medicine.
China and Turkey have also dispatched humanitarian aid flights in recent days.
Mr Sharif has promised funds would be spent transparently and said any delay in aid “will be devastating for the people of Pakistan."
- with AP inputs