Nearly half a million Pakistanis are estimated to have fled fighting between soldiers and militia on the Afghan border with more than 264,000 registered for aid, officials said Monday.
Authorities say increasing numbers of women and children are fleeing Khyber, one of the seven districts that make up Pakistan's semi-autonomous tribal belt, which is considered a stronghold of Al-Qaeda and Taliban.
More than 500 families are arriving on a daily basis at Jalozai camp, near the northwestern city of Peshawar, camp administrator Noor Akbar told AFP.
"We have registered 56,842 families or 264,253 individuals so far since the offensive was launched in January," Akbar said.
"We expect more will flee as the fighting continues."
Save the Children said it estimated that 63,000 families, or nearly half a million people, have already been displaced from Khyber.
A spokesman said the charity's estimate was much higher than the number registered because most people chose to live outside the camp and because new arrivals were mostly women and children put off by long registration queues.
"Save the Children estimates that over 600,000 in total will be displaced if military operations continue -- among which over 300,000 are expected to be children," the charity said in a report.
Last month, the UN refugee agency said more than 181,000 people had fled the fighting and that 85 percent of those registered chose not live in Jalozai.
The fighting started on January 20 when government troops attacked militant groups in the Khyber.
Officials say the fighting is concentrated in a large area, home to scores of settlements, between Tirah valley and Bara town on the outskirts of Peshawar.
Government troops have struggled since 2009 to defeat Mangal Bagh, a former bus conductor who founded Lashkar-e-Islam, a militia known for kidnapping and extortion, and locked in a turf war with local Taliban.