Zimbabwe yesterday declared a national emergency over a cholera epidemic and the collapse of its health care system and state media reported the government was seeking more international help to pay for food and drugs.

The failure of the health system is one of the most devastating effects of the country's economic collapse.

Facing the highest inflation in the world, Zimbabweans are struggling just to eat and find clean drinking water. The United Nations says cholera has killed more than 500 people since August because of a lack of water treatment and broken sewage pipes.

Residents are receiving little help from the government, which has been paralysed since disputed March elections as President Robert Mugabe and the opposition wrangle over a power-sharing deal.

"Our central hospitals are literally not functioning," Minister of Health David Parirenyatwa told a meeting of government and international aid officials, the state-run Herald newspaper reported.

Aid agencies and donors must step up their response, said Matthew Cochrane, regional spokesman for the Red Cross.

"This is about supporting the people of Zimbabwe," Cochrane said, adding that aid should include water treatment plants and more medical staff.

Gordon Brown, long one of Mugabe's sharpest critics, agreed that Zimbabwe was facing an emergency and nations must help.

"Mugabe's failed state is no longer willing or capable of protecting its people," the Prime Minister said. "The international community's differences with Mugabe will not prevent us doing so - we are increasing our development aid, and calling on others to follow."

Britain has offered £3m and set aside a further £7m in relief aid for Zimbabwe to provide medicine, fund basic health services and help prevent more cholera outbreaks.

The European Commission is providing more than £6m for drugs and clean water and the Red Cross shipped in more supplies on Wednesday to fight the cholera outbreak.

The Herald said the government declared the state of emergency at Wednesday's meeting and appealed for money to pay for food, drugs, hospital equipment and salaries for doctors and nurses.

Walter Mzembi, the deputy water minister, said his ministry had only enough chemicals to treat water nationally for 12 more weeks.

High levels of cholera are common in the region, but Cochrane said it was hitting a population already weakened by hunger and poverty. The death toll could be much higher than the official figures, he added, because many deaths in rural areas were not being recorded.

More and more Zimbabweans are also seeking cholera treatment in neighbouring South Africa.

Besides shortages of food and other basics, even cash is scarce.

A new ZW$100m note went into circulation yesterday in an attempt to ease the cash crunch and the daily withdrawal limit was increased to ZW$100m a week - enough to buy 10 gallons of clean water.

The new bills and withdrawal limits prompted big queues at banks yesterday.-AP