A United Nations mission in Zimbabwe to assess the country's food production levels has been called off by Preisdent Robert Mugabe's government, UN officials said Sunday.

Kevin Farrell, chief representative of the World Food Programme, the UN's famine relief arm, confirmed reports that three teams, made up of two WFP agronomists and one from the Food and Agriculture Organization, and locally-based UN experts, had been ordered back to Harare last week after only four days in the field.

"All we know is what we have been told verbally," he said. "We still have to be officially told that this has happened and hopefully we will get some better clarification why."

UN officials said the three assessment teams were in different famine-stricken areas of the country when one of the government officials received a call on his mobile telephone, telling him to order the UN personnel to withdraw.

The UN and Zimbabwean officials were to produce a joint assessment of this year's farm production, the usual preliminary to a mid-year launch of a new international appeal for famine relief in Zimbabwe.

"It's very strange, given that they had given us written approval to carry out the assessment," said Mike Higgins, the head of the WFP in South Africa.

Famine struck the country in 2002 in the wake of violent and illegal seizures of nearly all 11-million hectares of productive white-owned land that critics say has destroyed an agricultural industry that earned Zimbabwe the reputation of being "the breadbasket of Africa".

The government has claimed that 17-million tons of maize, the national staple, will be produced this year.

The forecast is double last year's output despite low early rains, flooding in many areas, critical shortages of seed and fertilizer and the failure of new settlers to move onto vast areas of once- productive land.

Last month the Usaid-funded Famine Early Warning Network System (Fewsnet) described the forecast as "optimistic" and said that there was "no independent and credible way to cross-check the government estimates".

It said famine was still "widespread and serious" and 4-million people were still being fed by the WFP and other donor agencies.

The government informally told the WFP it wants the international famine relief operation to finish by the end of next month because Zimbabwe alone plans to feed its 12-million people.

Fewsnet said food distribution operations by state agencies were "erratic and grossly inadequate" and they were "not up to the challenge" of matching the UN's sophisticated operations.

Observers say that an independent UN crop survey would expose the worsening slump in agriculture, giving the lie to Mugabe's repeated claims that his "land reform programme" has been "an unqualified success" and that a "bumper harvest" is about to be reaped.

Critics fear that the government plans to take over famine relief operations so that it can use its control over food supplies to force hungry Zimbabweans to vote for Mugabe's ruling Zanu(PF) party in parliamentary elections next year.

Observers say there is ample record of government agencies withholding famine relief from starving opposition supporters, and of using it to buy votes in local elections in the last two years.

The practice of ruling party officials handing out bags of maizemeal to voters as they leave polling stations is regarded as commonplace.

The UN faces antagonism and a lack of cooperation from the government, including raids by ruling party vigilantes on UN food stockpiles, the closure of WFP offices in famine stricken areas and barring agencies from hungry opposition areas.

"The only place where you see this kind of aggression and mistrust is in countries like North Korea," said a Western diplomat. - Sapa-DPA