Thousands of people are streaming into camps seeking refuge from the conflict between Pakistan's army and Taliban rebels in the country's north-west.
Most of the civilians come from Mingora, the main city in Pakistan's Swat valley, where a curfew was lifted on Friday to allow residents to leave.
Reports say the road out of Mingora is filled with buses and trucks, each one overcrowded, with people on the roofs.
The United Nations says 830,000 people have left their homes within the past month.
The total number of people internally displaced within Pakistan over the past 12 months has risen to about 1.3 million.
An estimated 80,000 of those are now living in camps run by the UN High Commission for Refugees, based around the city of Mardan.
Pakistan's Prime Minister Yousuf Raza Gilani has described the situation as the country's worst refugee crisis since the bloody partition of India and Pakistan in 1947 at the end of colonial rule.
The army has blockaded the town of Mingora, the administrative hub of the Swat valley, previously a popular tourist and ski resort but in recent years the focus of a Taliban uprising.
The BBC reports the first wave of people left Mingora a week ago, and food and other vital supplies are now scarce inside the city.