SUKKUR (AFP) – The United Nations is launching an appeal to help 13.8 million people hit by one of the world's worst humanitarian disasters after floods paralyzed parts of Pakistan and fanned fears of disease.

The UN Office for the Coordination of Humanitarian Affairs said the disaster had eclipsed the scale of the devastating 2004 Indian Ocean tsunami, the 2005 earthquake in Pakistan and the January 2010 earthquake in Haiti put together.
About 1.5 million people have been evacuated in the south and 1.5 million hectares of valuable farmland destroyed in central Punjab province while the worst hit has been the northwest, already struggling with Taliban violence.
“We will soon issue an... appeal for several hundred million dollars to respond to immediate needs,” UN chief Ban Ki-moon announced, stressing that medium- and long-term assistance “will be a major and protracted task.”
UN special envoy Jean-Maurice Ripert said hundreds of millions of dollars would be needed to address the urgent humanitarian needs and billions for the rehabilitation and reconstruction of infrastructure and livelihoods.
Parts of the northwestern Swat valley, where Pakistan fought a major campaign to flush out Taliban insurgents last year, were still cut off Tuesday by road as were parts of the country's breadbasket in Punjab and Sindh.
“This is a major disaster of enormous magnitude,” said UN emergency relief coordinator John Holmes, who is to launch the appeal in New York on Wednesday for what is likely to be one of the biggest UN relief efforts in history.
UN officials were at pains to stress that aid would focus on six million people who need direct humanitarian assistance in order to survive.
Spokeswoman Elisabeth Byrs said the figure of 14 million was a broader measure given by Pakistani authorities that included the direct and indirect impact, extending from the homeless to longer term damage such as crop losses.
The United Nations has warned that children are among the most vulnerable with diarrhea the biggest health threat and measles a serious concern.
The world body believes 1,600 people have died in Pakistan's floods but the Pakistani government has confirmed 1,243 deaths. Both numbers are dwarfed by the 220,000 killed in the December 2004 tsunami in Asia.
International aid agency Oxfam said the floods were a “mega disaster” that required the world to mount a “mega response”.
Weather cleared Tuesday, allowing Pakistani, US and Afghan helicopters to help distribute relief items and rescue people stranded in the northwest, said one military official.
“If we have a second wave, mortality will climb. Life-saving health assistance is a priority to ensure that we do not have a second wave of mortality,” said Martin Mogwanja, the UN coordinator in Pakistan.
In the south, there are warnings in towns and cities for people to remain on alert, but water levels were beginning to drop at the Guddu barrage and the meteorological office has forecast only scattered rain for the next two days.
“For the last three nights I have not have a good sleep as the water level in the river is constantly increasing. I do not know whether it is safe here or not,” shopkeeper Allah Rakhio told AFP in the city of Sukkur in Sindh.
Survivors have lashed out at authorities for failing to come to their rescue, piling pressure on Pakistan's cash-strapped administration straining to contain Taliban violence and an economic crisis.
At the Ali Wahan camp about 20 kilometres (13 miles) east of Sukkur, there were hardly a dozen flood survivors and a clinic with limited stocks of basic medicine, but no life-saving drugs.
“There are no facilities for families to live in this camp. My husband has gone to arrange some transport and we'll leave,” said Mai Jannat, 35.
Doctor Nazir Ahmed at the camp said patients were suffering from gastroenteritis, stomach and eye diseases.
People have also been unwilling to abandon their livestock despite insistence from navy personnel to evacuate.