The U.N. refugee agency says the displacement of people in Pakistan's North West Frontier Province is taking place with breathtaking speed.  The UNHCR says nearly one million people have fled their homes since the government began its offensive against Taliban militants in and around the Swat Valley in late April. Officials are worried about the long term impact of the displacement.

Pakistan's prime minister has described the current exodus from Swat Valley and neighboring areas as the country's worst refugee crisis since the bloody partition of India and Pakistan in 1947 at the end of colonial rule.

U.N. refugee spokesman William Spindler says just 80,000 of the nearly one million people his agency has already registered are now in camps.  He says the rest are staying with host families or in rented accommodations. 

He says High Commissioner Antonio Guterres, who currently is in Pakistan, warns the displacement crisis could have an enormous destabilizing impact on the affected populations.  He says hundreds of millions of dollars will be needed to support the displaced.

Spindler says the UNHCR has responded quickly to the unfolding humanitarian crisis.

"We already had a major presence in Pakistan after decades of helping Afghan refugees, and we started distributing aid from stocks in the country as soon as the dimensions of the current crisis became clear," he said. "We have helped establish new camps for the displaced as well as reception and registration centers.  Hundreds of spontaneous settlements have sprung up in schools, colleges, flour mills, stadiums, parks, private land and other sites.  UNHCR has visited many of these to assess needs." 

Pakistani authorities temporarily lifted a curfew in Swat Valley on Friday to allow civilians to flee the conflict zone.  Thousands of people took advantage of the lull in fighting to seek refuge in safer areas.

The U.N. Children's Fund representative in Pakistan, Martin Mogwanja, says he has heard reports that Taliban militants have shot at civilians leaving Swat Valley or have been blocking civilians from fleeing other areas.

He says he cannot confirm these reports as UNICEF and other aid agencies are not on the ground.  Mogwanja was speaking to journalists in Geneva on a telephone link from Islamabad.

"Due to security considerations for humanitarian workers, which has been brought about by the facts that specific threats have been issued by the armed militants to non-governmental organizations, both national and international, threatening humanitarian agencies who continued to operate in those areas, all the NGOs and the humanitarian workers have had to leave these areas," he said. 

Mogwanja says secondary reports from people who managed to get out of Swat Valley indicate the population left behind is having a very difficult time.  He says electricity is reported to have been cut and the food supply is limited.

He says the major hospital near Mingora, the capital of Swat had to be closed.  He says the doctors left because of insecurity.  He says he is very worried that people needing medical care will not get it.