* Diseases create new set of dangers
* Concerns about cholera after one confirmed case
* Missing the 4.5 percent GDP growth target
* Exodus from city in Sindh
(Adds confirmed case of cholera, FAO estimate on crop damage)
By Akhtar Soomro
SUKKUR, Pakistan, Aug 13 (Reuters) - Disease outbreaks pose grave risks to victims of Pakistan's worst floods in decades, aid agencies said on Friday, causing fresh concern about already complicated relief efforts.
The floods, triggered by torrential monsoon downpours, have engulfed Pakistan's Indus river basin, killing more than 1,600 people, forcing two million from their homes and disrupting the lives of 14 million people, or 8 percent of the population.
At a hospital in Mingora, the main town in Swat valley, an official who asked not to be named told Reuters one case of cholera was confirmed. A German humanitarian organisation said there were also six suspected cases there.
An epidemic could create another disaster for Pakistan.
A health crisis would tax aid agencies which are facing vast logistical challenges because of the damage and illness caused by the widespread flooding.
The United Nations is worried about water-borne diseases. There have been 36,000 suspected cases of potentially fatal acute watery diarrhoea reported so far. It says the floods have affected about one-third of Pakistan.
"This is a growing concern. Therefore we are responding with all kinds of preventative as well as curative medication ... for outbreaks," Maurizio Giuliano, the U.N. humanitarian operation spokesman, told Reuters.
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Floods have roared down from the northwest to Punjab province to southern Sindh.
U.N. Secretary-General Ban Ki-moon is expected to visit Pakistan over the weekend to discuss the crisis.
Pakistan's overwhelmed government has been on the defensive after criticism of its response to one of the worst catastrophes in the country's history.
The military, which has ruled U.S. ally Pakistan for more than half of its history, has swung into action.
President Asif Ali Zardari has started visiting flood victims after being attacked for leaving for meetings with European leaders as the disaster unfolded, and not cutting his trip short. Zardari said he lobbied for international aid for flood victims on his trip.
Despite the criticism of the government's handling of the floods, political analysts rule out a military grab for power, or the government's downfall over the disaster. But social unrest is possible, the analysts said.
In Punjab, Pakistan's bread basket, people scuffled over relief supplies.
"There may be severe shortages too and riots could well break out," said independent economist Meekal Ahmed. He predicted the fiscal deficit would come under strain and amount to about 8 percent of GDP -- twice this year's target.
Villages have been wiped away, leaving some with just a patch of land to stand on. Pakistanis are still at the mercy of the weather and fresh downpours could bring further destruction and displacement.
Residents of the city of Jacobabad in Sindh were taking no chances. "Out of a population of 300,000, about 225,000 people have left for nearby cities and towns in the past few days," city administrator Kazim Jatoi told Reuters.
Panic followed warnings that a major surge was heading there from a breach in an embankment along the Indus River.
The International Monetary Fund has warned of major economic harm and the finance ministry said the country would miss this year's 4.5 percent gross domestic product growth target though it was not clear by how much.
World Bank President Robert Zoellick said on a visit to Latvia that the floods were likely to have destroyed crops worth around $1 billion. "All of us will have to pitch in to help," he told a news conference.
Floods have damaged about 700,000 hectares of crops, mainly rice, maize, cotton, and sugarcane, jeopardising the country's main exports, the United Nations' food agency said.
The losses at household level could also have a negative impact on planting of the 2010/11 season due to start in October/November because of the loss of seeds and other agricultural basics, the Food and Agriculture Organisation said.
Prices for food still available in markets are soaring.
"Where will I get money from? Rob a bank? Carry out an armed robbery?" grumbled flood survivor Mehr Din, 55. (Additional reporting by Aija Braslina in Stockholm, Svetlana Kovalyova in MILAN, Adrees Latif in MULTAN, Junaid Khan in MINGORA, Sahar Ahmed in KARACHI, Zeeshan Haider, Shiza Shahid and Augustine Anthony in ISLAMABAD and Stefanie Huber in MUNICH; Writing by Michael Georgy)