The UN says Zimbabwe has not allowed UN staff to assess the state of the country's crops and food stocks.Three UN World Food Programme teams who were in areas of greatest need have been withdrawn to the capital, Harare.

In March, the Zimbabwean government produced a crop projection that aid agencies dismissed as impossibly high.

A former food exporter, Zimbabwe has had to rely on food aid since it began controversial land reform by taking land from white commercial farmers.

International donors refused to promise more aid until reliable information was forthcoming. Critics believe that politics is behind the government's current stand.

President Robert Mugabe is determined to end reports that his land reforms have left the country desperately short of food, before next year's parliamentary elections.

There are reports that the president has won promises of foreign aid from a number of developing world allies.

And this, it is said, will be used to bridge the gap between Zimbabwe's own crop and the needs of its people.

President Mugabe has been repeatedly criticised for using food as a political weapon. But if the critics are right, imported grain will only be provided to government supporters, guaranteeing victory in next year's elections.