Victims of Pakistan's floods on Tuesday queued at hospitals where scant resources were available to treat a rising number of patients.

Aid agencies fear disease, food shortages and malnutrition may create new crises as people head back to their shattered towns and villages to rebuild their homes and lives.

Whatever stock of medicines we have is about to finish and the number of patients will increase in the coming days, said Ashiq Hussain Malik, medical superintendent of Muzaffargarh's main district hospital in Punjab province.

Nearly 60 percent of patients are suffering from gastroenteritis, diarrhoea, skin and eye infections and the patients who are coming here are in a pretty bad condition.

Economic growth, forecast at 4.5 percent this fiscal year, is now predicted at anything between zero and 3 percent.

Anthony Lake, executive director of the United Nations Children's Fund, said the floods were a children's emergency.

Nearly 8.6 million children, roughly 50 percent of the total affected population has been hit by the flooding, he told a news conference after touring flooded areas.

These children are in desperate need and they must be reached, fed, given water, vaccinated, protected from diseases.

Some Pakistanis have grown increasingly angry with the sluggish government response, and are turning to Islamist charities, some of them tied to militant groups.

The U.S. State Department says it has been told of a threat from Islamist militants to foreign aid workers, complicating the already extremely difficult task of relief and reconstruction.

Aid agencies are warning that with so much farmland under water in a country which is heavily dependent on agriculture the crisis in Pakistan could persist for months.

At least 3.2 million hectares (8.4 million acres), about 14 percent of Pakistan's entire cultivated land, have been damaged.

We could be looking at a year of food shortages and high food prices, said Josette Sheeran, executive director of the World Food Programme (WFP).

Muzaffargarh hospital is treating 1,000 flood victims. People lay on the floor or their own rope beds because of limited space.

I came to hospital around dawn and I'm still waiting for my number, Naseem Bibi said as her five-year-old daughter, suffering from diarrhoea, slept on the ground.

(Additional reporting by Myra MacDonald in Kot Addu, Augustine Anthony in Islamabad, Sahar Ahmed in Karachi, Asim Tanveer in Multan; Writing by Michael Georgy; Editing by Sanjeev Miglani)