Aid agencies said entire villages had been washed away in the region's worst flooding for 80 years.
Unicef said 3m people had been affected and 1,400 had been killed. Other estimates said between 800 and 1,500 had died, with 27,000 still trapped.
Renewed rain on Tuesday slowed the relief effort, with criticism rising of the pace of the government response.
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In pictures: Flood damage South Asia's deadliest threat? In Swat, where thousands are still rebuilding after a major military operation against Taliban rebels during 2009, the flooding has brought down bridges and left communities cut off.wow power leveling wow powerleveling cheap wow gold world of warcraft power leveling power leveling ffxiv power leveling ffxiv gil ffxiv power leveling ffxiv gold ffxiv power leveling ffxiv gils"There is no aid agencies here at the moment - I haven't seen anyone, because more than 25 bridges have been swept away. These are the metal bridges for carrying transport."
Adnan Khan, a spokesman for the disaster management authority in the worst-affected province, Khyber-Pakhtoonkhwa, told Reuters news agency that logistics were now an immense challenge.
"The entire infrastructure we built in the last 50 years has been destroyed," he said.
The BBC's Lyse Doucet, in Islamabad, says the flooding would be a challenge in any country, but is a growing crisis for a country like Pakistan, already suffering economic woes and a Taliban insurgency.
Unicef said 3m people had been affected and 1,400 had been killed. Other estimates said between 800 and 1,500 had died, with 27,000 still trapped.
Renewed rain on Tuesday slowed the relief effort, with criticism rising of the pace of the government response.
Related storiesAPB Cash
APB Gold
APB Power leveling
In pictures: Flood damage South Asia's deadliest threat? In Swat, where thousands are still rebuilding after a major military operation against Taliban rebels during 2009, the flooding has brought down bridges and left communities cut off.wow power leveling
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ffxiv gils"There is no aid agencies here at the moment - I haven't seen anyone, because more than 25 bridges have been swept away. These are the metal bridges for carrying transport."
Adnan Khan, a spokesman for the disaster management authority in the worst-affected province, Khyber-Pakhtoonkhwa, told Reuters news agency that logistics were now an immense challenge.
"The entire infrastructure we built in the last 50 years has been destroyed," he said.
The BBC's Lyse Doucet, in Islamabad, says the flooding would be a challenge in any country, but is a growing crisis for a country like Pakistan, already suffering economic woes and a Taliban insurgency.