The International Committee of the Red Cross says it is gravely concerned about the humanitarian situation in Swat Valley in Pakistan where the army has driven out the Taliban.
After its first assessment, the Red Cross said civilians need immediate and comprehensive help and relief teams must be allowed unimpeded access.
The agency said most medical facilities were out of action and there was no running water or electricity. Food is also scarce.
However, the army says essential services are being restored in the area's main town, Mingora - large parts of which have been reduced to rubble.
An estimated 2.5 million people have fled their homes in the Swat Valley since military operations began more than a month ago.
Confidence over nuclear security
Pakistan says it is confident its nuclear assets will not fall into militant hands. Defence Secretary Syed Athar Ali says security is constantly being reviewed, with assistance from friendly countries.
He did not name those countries. However, last week, a source close to French President Nicolas Sarkozy said France and Pakistan are negotiating a partnership, including nuclear cooperation.
Nuclear security has been a question mark since a Pakistani scientist Abdul Qadeer Khan, confessed to selling nuclear secrets to Iran, North Korea and Libya in 2004.
Mr Ali told a security forum in Singapore on Sunday that the Swat and Buner valleys and adjoining northwest districts are almost clear of the Taliban.
Remaining pockets of resistance would hopefully be cleared in the "next two to three days."
Mr Ali also said the army will stay in the Swat Valley beyond current military operations, until the police take control there.