Fear of water-borne diseases -- such as cholera and malaria -- growing due to lack of clean water.
Fears were growing about outbreaks of disease among 2.5 million people affected by Pakistan's worst floods in 80 years after monsoon rains killed many hundreds of people. Islamist charities, some with suspected ties to militants, stepped in Monday to provide aid, piling pressure on a government criticized for its response to the disaster.
Unprecedented rains triggered floods and landslides, sweeping away thousands of homes and devastating farmland in one of Pakistan's most impoverished regions, already hard hit by years of Talibanand al-Qaida-linked violence.
Pakistani officials warn that a lack of drinking water is spreading disease, including cholera and malaria, and say they are working to move people from affected areas such as Swat, the scene last year of an offensive against the Taliban.
The official death toll stood at 1,500 people Monday, but many devastated areas are cut off by destroyed roads and bridges.
The International Committee of the Red Cross said that up to 2.5 million people across Pakistan had been affected by the flooding and said the death toll could end up in the thousands.
"In the worst-affected areas, entire villages were washed away without warning by walls of flood water," it said, noting that thousands of people "have lost everything."
It said the coming disease could make this a disaster to rival the 2005 earthquake that hit Pakistani Kashmir, killing an estimated 75,000 people
"There are 774 deaths registered with us, but the total number killed in the flood is 1,200 to 1,500," Mian Iftikhar Hussain, the information minister for northwest province Khyber Pakhtunkhwa, told a news conference in Peshawar.
Hussain said the floods had displaced 500,000 people in Khyber Pakhtunkhwa province and put the figure of people affected by the floods at more than 1.5 million.
Syed Zahir Ali Shah, health minister for the province, said about 100,000 people, mostly children, were already suffering from illnesses.
"They don't have drinking water or food. They said there have been some visible signs of water-borne diseases," said Muhammad Ali, a spokesman for the charity World Vision.
"We are getting patients with trauma, gastroenteritis, skin diseases and dehydration," doctor Shoaib Mohammad said at a small 20-bed mobile clinic in Nowshehra.
Fifty-year-old Ajmair Shah went into shock after the floods destroyed his home in Nowshehra. He lay motionless in his hospital bed, staring into the air.
"My house was swept away by the flood, nothing is left there. I have lost everything," he said and started weeping.
People at the camp said there were no proper latrines or bathrooms and that the only respite from the crushing heat was plastic hand fans. Most of them fled in the clothes they were wearing, and many children roamed around naked.
The floods are testing an administration heavily dependent on foreign aid and which has a poor record in crisis management -- whether fighting Taliban insurgents or easing chronic power cuts.
Rescuers are struggling to distribute relief to tens of thousands of people trapped in submerged areas where destroyed roads and bridges make access difficult.
Islamist charities believed to have ties with militants may gain support if their relief efforts pay off, as they did after the Kashmir temblor.
"They throw food at us as if we are animals and not humans," one man, Ilyas Khan, said, complaining there was no proper system of distribution.
Flood victims condemned authorities over sluggish relief, shouting "give us aid sent by foreign countries" and "death to the corrupt government."
Many in the path of the floods scrambled to save their livestock. One man swam across heavy currents with his chicken tied around his neck. In one town, there were more than 100 bloated buffalo carcasses, raising the spectre of disease.
Salman Shahid, spokesman for the Falah-i-Insaniat Foundation (Foundation for the Welfare of Humanity), said the Islamist group had set up 13 relief and six medical camps, and a dozen ambulances were providing emergency treatment. Several other Islamist groups are also helping out with the relief effort.
Falah-i-Insaniat is believed to have ties to Jamaat-ud-Dawa charity, which the UN Security Council banned last December for its alleged links with Lashkar-e-Taiba, the group blamed for the 2008 attack on the Indian city of Mumbai.
Some analysts expressed doubts that Islamist groups and their militant wings could capitalize on the disaster because army offensives have weakened them. Others said the Islamists' camps had set a dangerous precedent.
"It is very likely that they will exploit the governance vacuum, in the wake of this tragedy, to fuel their own recruitment," said columnist Huma Yusuf.
UN Secretary-General Ban Ki-moon pledged aid of up to $10 million dollars for those affected. The U.S. government announced a $10-million aid pledge and has rushed helicopters and boats to Pakistan. China has also promised $1.5 million. Britain pledged $8 million Monday to help provide safe drinking water and sanitation.
Khyber Pakhtunkhwa chief minister Amir Haider Hoti said the floods were "unprecedented" and warned it could take up to 10 days to assess the overall number of dead and displaced.
"The entire infrastructure we built in the last 50 years has been destroyed," said Adnan Khan, spokesman for the Disaster Management Authority in Khyber-Pakhtunkhwa.
Pakistan's meteorological service said much more rain is expected across the northwest in the next few weeks.
The National Disaster Management Authority said troops had rescued more than 28,000 people in Khyber Pakhtunkhwa by helicopter and boat.
