Islamabad (Deutsche Presse-Agentur) -- The United Nations said on Monday that millions of people were facing hunger and disease after the worst floods in Pakistan's history.

The floods triggered by heavy monsoon rains have submerged hundreds of villages and towns, destroyed millions of hectares of crops and affected more than 15 million people.

"We are working hard to supply food to the flood victims staying at the relief camps and in the open but there are still millions who are getting little or no food at all," said Amjad Jamal, a spokesman for the UN's World Food Program.

Jamal said many areas were still cut off by destroyed bridges and roads.

"We managed to reach Kohistan and Shangla district in the north-western province of Khyber-Pakhtunkhwa around two weeks after these were hit by floods. People are running out of stocks and we are still not able to provide them as much food as they need," he said.

The local authorities and UN aid workers were using helicopters and mules to transport food to the mountainous district of Kohistan.

The United Nations on Monday appealed for a further 40 helicopters to carry food to tens of thousands of people still stranded.

The organization has expressed concern for the flood survivors' increasing health problems.

Maurizio Giuliano, a spokesman for the UN's Office for the Coordination of Humanitarian Affairs in Pakistan, said that some 1.5 million flood victims were being treated for diarrhoea, skin diseases and other problems.

The flood waters have started to recede from northern and central Pakistan but the swollen Indus River was still affecting the southern province of Sindh, where dozens more villages have been submerged over the last 24 hours.

Pakistan's chief meteorologist said on Monday that "low to high flood situation will persist for the next two to three days."

The government has said it will need billions of dollars to reconstruct the country's infrastructure and rehabilitate the displaced people.

The international community has so far provided more than 815 million dollars in immediate aid.

Copyright 2010 dpa Deutsche Presse-Agentur GmbH