Aid workers said Wednesday the disarray of the government of Zimbabwe is putting its most vulnerable citizens at risk as hunger and disease threatens to sweep the country.

Zimbabwe's Prime Minister Morgan Tsvangirai announced last week he was withdrawing indefinitely from a unity government that has been troubled from the moment its ministers were sworn in in February.

Tsvangirai cited "the fiction of the credibility and integrity" of his partnership with longtime President Robert Mugabe — a description likely to undermine his own efforts to persuade donors to help Zimbabwe recover from economic collapse.

Charles Abani, head of Oxfam-UK's operations in southern Africa, say Zimbabwe needs coordinated, "robust leadership" to avert a repeat of the cholera epidemic and widespread hunger it faced last year.

"We are obviously concerned that the government of national unity continues to work," Abani said in an interview with The Associated Press.

Peter Salama, head of the U.N. children's agency office in Zimbabwe, called on Zimbabwe's leaders to overcome their political differences and "rally around the issues facing Zimbabwe's children today, and that its access to basic services" like schools and clinics, which have been devastated by the country's economic collapse.

Salama told AP it would be "tragic" if the political impasse leads the international community to decide Zimbabwe is too risky to continue to invest in.

The European Union on Wednesday asked Zimbabwe's neighbors to help resolve the country's political problems and expressed concern over "continued politically motivated harassment of" members of Tsvangirai's party. Last month, the first visit by a high-level EU delegation since 2002 ended with a declaration that Europe would not resume development aid until more is done to implement the power-sharing agreement and restore human rights.

Before the unity government was formed, foreign governments hesitated to send aid and development money to Zimbabwe. The funds they did send were channeled through independent agencies, making coordination difficult. At one point, relations with the outside world deteriorated so much, ZANU-PF accused independent groups of supporting opposition activists and barred them from distributing aid for three months. The ban was lifted in late August, 2008.

Aid workers now have been called in to help even in prisons. In recent months, the international health agency Medecins Sans Frontieres has been providing food, clean water and medical care to inmates in 15 prisons, said Wim Fransen, head of MSF-Brussels in Zimbabwe.

"What is important to know is that the crisis is still here and there is still a need for donors to fund organizations," Fransen said.

What's known as the hungry season, when food from the year's harvest begins to run out, is expected to hit in December of January. Last year, more than 5 million people needed food aid. Oxfam's Abani said it was likely to be less than 3 million this year, still significant in a population of about 8 million.

Reports of cholera have already emerged this year in Zimbabwe. Rains expected in the coming months will overflow sewers, worsening the risk of the water-borne disease's spread. A cholera outbreak that started in August 2008 and took months to bring under control killed some 4,000 people.

The rainy season is also the breeding season for the mosquitoes that carry malaria. The U.N.'s Roll Back Malaria Partnership warned in January of a possible surge in malaria cases and deaths in Zimbabwe. Since then, said spokesman Herve Verhoosel, it has been able to work with the new government to ensure insecticide was distributed before the rains.

The next step, Verhoosel said, will be getting a new generation of malaria medication into hospitals and clinics across Zimbabwe before the rains. But the new medication is more expensive and Verhoosel said Roll Back Malaria is concerned that donations to buy the drugs will drop amid questions about the viability of the Tsvangirai-Mugabe partnership.