"The displacement of these people, three-quarters of whom are women and children, was triggered by the Pakistani military's operations against armed insurgents," Xinhua quoted UN spokesman Stephane Dujarric as saying.
"Nearly 100,000 people have also fled to Afghanistan's Khost province to seek shelter," Dujarric said.
The UN Office for the Coordination of Humanitarian Affairs (OCHA) said that food, medicine and sanitation services are being provided to the displaced.
The World Food Program (WFP) said that it is distributing food from six locations to reach all the families, with two-week rations of wheat flour, pulses, fortified vegetable oil and salt, as well as high-energy biscuits.
The government has provided the WFP with 25,000 metric tonnes of wheat.
The WFP has appealed for $29 million for its relief operations through the end of the year.