The International Committee of the Red Cross says it is "gravely concerned" about the situation for civilians in the Swat valley in the North-West Frontier Province.
The Swiss-run organisation said in a statement on Sunday that there should be a "prompt and comprehensive" humanitarian response for people caught in the fighting between Pakistani troops and Taliban rebel forces.
A team of ICRC delegates that visited the area on Saturday said they were alarmed by what they had seen.
"People have been blocked for weeks," said Daniel O'Malley, who led the team.
"There is no running water, no electricity, and food is scarce. There is no fuel left for generators and most medical facilities in the district are no longer functioning."
The statement from ICRC headquarters in Geneva said access to Swat and other districts affected by the fighting remained too limited to meet the needs of the people affected.
In compliance with the JTI standards